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Binding of branched-chain 2-oxo acids to bovine serum albumin. Livesey G,Lund P The Biochemical journal 1. Binding of branched-chain 2-oxo acids to defatted bovine serum albumin was shown by gel chromatography and equilibrium dialysis. 2. Equilibrium-dialysis data suggest a two-side model for binding in Krebs-Henseleit saline at 37 degrees C with n1 = 1 and n2 = 5. Site association constants were: 4-methyl-2-oxovalerate, k1 = 8.7 x 10(3) M-1, k2 = 0.09 x 10(3) M-1; 3-methyl-2-oxovalerate, k1 = 9.8 x 10(3) M-1, k2 = 0.08 x 10(3) M-1; 3-methyl-2-oxobutyrate, k1 = 1.27 x 10(3) M-1, k2 = less than 0.05 x 10(3) M-1. 3. Binding of 4-methyl-2-oxovalerate to defatted albumin in a phosphate-buffered saline, pH 7.4, gave the following thermodynamic parameters: primary site delta H0(1) = -28.6kJ . mol-1 and delta S0(1) = -15.2J . mol-1 . K-1 (delta G0(1) = -24.0kJ . mol-1 at 37 degrees C) and secondary sites delta H0(2) = -25.4kJ . mol-1 and delta S0(2) = -46.1J . mol-1 . K-1 (delta G0(1) = -11.2kJ . mol-1 at 37 degrees C). Thus binding at both sites is temperature-dependent and increases with decreasing temperature. 4. Inhibition studies suggest that 4-methyl-2-oxovalerate may associate with defatted albumin at a binding site for medium-chain fatty acids. 5. Binding of the 2-oxo acids in bovine, rat and human plasma follows a similar pattern to binding to defatted albumin. The proportion bound in bovine and human plasma is much higher than in rat plasma. 6. Binding to plasma protein, and not active transport, explains the high concentration of branched-chain 2-oxo acids leaving rat skeletal muscle relative to the concentration within the tissue, but does not explain the 2-oxo acid concentration gradient between plasma and liver. 10.1042/bj2040265
Plasmodium falciparum possesses organelle-specific alpha-keto acid dehydrogenase complexes and lipoylation pathways. Günther S,McMillan P J,Wallace L J M,Müller S Biochemical Society transactions The human malaria parasite Plasmodium falciparum possesses a single mitochondrion and a plastid-like organelle called the apicoplast. Both organelles contain members of the KADH (alpha-keto acid dehydrogenase) complexes--multienzyme complexes that are involved in intermediate metabolism. In the asexual blood stage forms of the parasites, the alpha-ketoglutarate dehydrogenase and branched chain KADH complexes are both located in the mitochondrion, whereas the pyruvate dehydrogenase is exclusively found in the apicoplast. In agreement with this distribution, Plasmodium parasites have two separate and organelle-specific pathways that guarantee lipoylation of the KADH complexes in both organelles. A biosynthetic pathway comprised of lipoic acid synthase and lipoyl (octanoyl)-ACP:protein Nepsilon-lipoyltransferase B is present in the apicoplast, whereas the mitochondrion is supplied with exogenous lipoic acid, and ligation of the metabolite to the KADH complexes is accomplished by a lipoate protein ligase A similar to that of bacteria and plants. Both pathways are excellent potential targets for the design of new antimalarial drugs. 10.1042/BST20050977
Genetic screening of Lactobacillus sakei and Lactobacillus curvatus strains for their peptidolytic system and amino acid metabolism, and comparison of their volatilomes in a model system. Freiding Simone,Gutsche K Amelie,Ehrmann Matthias A,Vogel Rudi F Systematic and applied microbiology A total of 51 Lactobacillus sakei and 28 Lactobacillus curvatus strains from different origins were screened for their potential to produce biogenic amines (BAs), and for their diversity of peptidolytic systems and specific aminotransferases (AraT, BcaT) that initiate amino acid conversion to volatiles relevant for aroma formation in meat products. The profiles of volatiles formed (volatilomes) were analysed in the headspace of fermentations by solid phase microextraction followed by GC-MS analysis. Tyramine-forming potential was detected only within L. curvatus and was strain-dependent. Histamine decarboxylase (HDC) activity could only be detected in one L. sakei strain, previously described as histidine decarboxylase positive (HDC(+)). Peptide transporters and peptidases were nearly ubiquitous in L. sakei and only a few strains lacked single peptidases. In L. curvatus, differences were detected in the occurrence of peptidase genes detected with PCR primers derived from L. sakei. All strains lacked known aminotransferases specific for branched-chain amino acids (BCAAs) and aromatic amino acids (ACAAs). Although L. sakei is suggested as a genetically very heterogenous species, and relatedness between L. curvatus and L. sakei at the genomic level is rather low, they appeared to be nearly uniform in the genes forming the peptidolytic system. The volatilomes of L. sakei and L. curvatus strains were qualitatively nearly identical. However, slight differences in the formation of single volatile compounds and the interaction with staphylococci may impact upon sausage fermentation which occurs over a period of many weeks. Among the compounds expected to contribute to the aroma were dimethyldisulphide, 3-methyl-1-butanol, acetic acid, 1-butanol and butanoic acid. 10.1016/j.syapm.2010.12.006
Combining TXRF, FT-IR and GC-MS information for identification of inorganic and organic components in black pigments of rock art from Alero Hornillos 2 (Jujuy, Argentina). Vázquez Cristina,Maier Marta S,Parera Sara D,Yacobaccio Hugo,Solá Patricia Analytical and bioanalytical chemistry Archaeological samples are complex in composition since they generally comprise a mixture of materials submitted to deterioration factors largely dependent on the environmental conditions. Therefore, the integration of analytical tools such as TXRF, FT-IR and GC-MS can maximize the amount of information provided by the sample. Recently, two black rock art samples of camelid figures at Alero Hornillos 2, an archaeological site located near the town of Susques (Jujuy Province, Argentina), were investigated. TXRF, selected for inorganic information, showed the presence of manganese and iron among other elements, consistent with an iron and manganese oxide as the black pigment. Aiming at the detection of any residual organic compounds, the samples were extracted with a chloroform-methanol mixture and the extracts were analyzed by FT-IR, showing the presence of bands attributable to lipids. Analysis by GC-MS of the carboxylic acid methyl esters prepared from the sample extracts, indicated that the main organic constituents were saturated (C(16:0) and C(18:0)) fatty acids in relative abundance characteristic of degraded animal fat. The presence of minor C(15:0) and C(17:0) fatty acids and branched-chain iso-C(16:0) pointed to a ruminant animal source. 10.1007/s00216-008-2038-4
Natural variability in acyl moieties of sugar esters produced by certain tobacco and other Solanaceae species. Phytochemistry A unique feature of glandular trichomes of plants in the botanical family Solanaceae is that they produce sugar esters (SE), chemicals that have been shown to possess insecticidal, antifungal, and antibacterial properties. Sugar esters of tobacco (Nicotiana tabacum) provide pest resistance, and are important flavor precursors in oriental tobacco cultivars. Acyl moieties of SEs in Nicotiana spp., petunia, and tomato are shown to vary with respect to carbon length and isomer structure (2-12 carbon chain length; anteiso-, iso-, and straight-chain). Sugar esters and their acyl groups could serve as a model to explore the basis of phenotypic diversity and adaptation to natural and agricultural environments. However, information on the diversity of acyl composition among species, cultivars, and accessions is lacking. Herein, described is the analysis of SE acyl groups found in 21 accessions of Nicotiana obtusifolia (desert tobacco), six of Nicotiana occidentalis subsp. hesperis, three of Nicotiana alata, two of N. occidentalis, four modern tobacco cultivars, five petunia hybrids, and one accession each of a primitive potato (Solanum berthaultii) and tomato (Solanum pennellii). A total of 20 different acyl groups was observed that were represented differently among cultivars, species, and accessions. In Nicotiana species, acetate and iso- and anteiso-branched acids prevailed. Straight-chain groups (2-8 carbons) were prominent in petunias, while octanoic acid was prominent in N. alata and N. × sanderae. Two unexpected acyl groups, 8-methyl nonanoate and decanoate were found in N. occidentalis subsp. hesperis. Longer chain groups were found in the petunia, tomato, and potato species studied. 10.1016/j.phytochem.2016.05.008
[alpha-Oxidation of 3-methyl-branched fatty acids: unraveling of a pathway]. Casteels M Verhandelingen - Koninklijke Academie voor Geneeskunde van Belgie Peroxisomes have an important role in lipid metabolism e.g. beta-oxidation of long and very long chain fatty acids, 2-methyl-branched fatty acids, dicarboxylic fatty acids, prostanoids and bile acid intermediates, and synthesis of ether lipids. Also the process of alpha-oxidation of 3-methyl-branched fatty acids, with phytanic acid (3,7,11,15-tetramethylhexadecanoic acid) as the best known example, occurs in peroxisomes. alpha-Oxidation is a process in which fatty acids are shortened by one carbon atom. The alpha-oxidation sequence of 3-methyl-branched fatty acids starts with an activation to the corresponding CoA-ester. Subsequently this acyl-CoA-ester undergoes a 2-hydroxylation by the peroxisomal phytanoyl-CoA hydroxylase (PAHX). In a third step the peroxisomal 2-hydroxyphytanoyl-CoA lyase (2-HPCL) splits the carbon carbon bond of the 2-hydroxy-intermediate into a 2-methyl(n-1)aldehyde and formyl-CoA, which is subsequently converted to formate and CO2. Finally the aldehyde is dehydrogenated by an aldehyde dehydrogenase to the corresponding acid, which, after its conversion to the acyl-CoA ester, can be a substrate for beta-oxidation. 2-HPCL is the first thiamine pyrophosphate dependent peroxisomal enzyme in mammals. Apart from 2-hydroxy-3-methylacyl-CoAs also 2-hydroxyacyl-CoAs are substrates for this enzyme. This indicates that the 2-hydroxy function but not the 3-methyl function of acyl-CoA esters is needed for 2-HPCL-activity. Long and very long chain 2-hydroxy fatty acids are constituents of brain cerebrosides and sulfatides, which mainly occur in myelin.
Impact of free hydroxylated and methyl-branched fatty acids on the organization of lipid membranes. Jenske Ramona,Lindström Fredrick,Gröbner Gerhard,Vetter Walter Chemistry and physics of lipids Differential scanning calorimetry (DSC) has been applied to study the effect of free hydroxylated and methyl-branched fatty acids on the physico-chemical properties of lipid membranes. First, the impact of free hydroxy fatty acids (HFAs) on dimyristoylphosphatidylcholine (DMPC) model membranes was monitored only as a function of chain length and position of the attached hydroxyl group. Second, racemic vs. enantiopure anteiso fatty acids (AFAs) and HFAs were investigated to address the question of which role does a fatty acid's chirality play on its membrane pertubing effect. The DSC thermograms revealed that the main gel to liquid-crystalline phase transition of the DMPC bilayers which results in a disordering effect of the lipid hydrocarbon chains was affected in different ways depending on the nature of the incorporated fatty acid. Long-chain 2- and 3-HFAs stabilized the gel phase by reducing the phase transition temperature (T(m)), whereas short-chain HFAs and long-chain HFAs with the hydroxy group remote from the head group stabilized the more disordered liquid-crystalline state. Additionally, we observed that enantiopure (S)-14-methylhexadecanoic acid ((S)-a17:0) and (R)-2-hydroxy octadecanoic acid and the corresponding racemates had contrary effects upon incorporation into DMPC bilayers. In both cases, the pure enantiomers alleviated the liquid-crystalline state of the biological model membrane. 10.1016/j.chemphyslip.2008.03.010
Equivalent chain lengths of all C4-C23 saturated monomethyl branched fatty acid methyl esters on methylsilicone OV-1 stationary phase. Kubinec Róbert,Blaško Jaroslav,Górová Renáta,Addová Gabriela,Ostrovský Ivan,Amann Anton,Soják Ladislav Journal of chromatography. A Isomer mixtures of monomethyl branched saturated C7-C23 fatty acid methyl esters (FAME) were prepared by performing a methylene insertion reaction to the straight chain FAME and this study model was completed by using commercially available standards of C4-C7 FAME. The equivalent chain lengths (ECL) of all 220 C4-C23 monomethyl branched FAME on OV-1 stationary phase were measured, achieving an average repeatability of ±0.0004 ECL units. The monomethyl branched FAME was identified by GC on the basis of regularity of the fractional chain lengths (FCL) dependence on the number of carbon atoms (C(z)) of individual homologous series of methyl 2-, 3-, …, 21-FAME. The prediction of retention of the first homologues, having the new position of methyl group beginning at higher carbon atoms number, and analogously for the second, third, fourth, and other members of the homologous series, allowed the dependence FCL=f(C(z)) for the first and subsequent members of beginning homologous of monomethyl derivatives of FAME. The identification was confirmed by mass spectrometry. All of the methyl isomers of FAME, which could not be completely separated by gas chromatography due to having a methyl group in surroundings of the middle of the carbon chain, were resolved by mass spectrometry using deconvolution in a SIM-mode. Measured gas chromatographic and mass spectrometric data were applied for identification of the monomethyl branched saturated FAME in tongue coating. 10.1016/j.chroma.2011.01.065
Branched medium-chain fatty acid profiling and enantiomer separation of anteiso-forms of teicoplanin fatty acyl side chain RS3 using UHPLC-MS/MS with polysaccharide columns. Journal of pharmaceutical and biomedical analysis This work reports on targeted UHPLC-tandem mass spectrometry methods for the chiral separation of anteiso-methyl branched fatty acids (aiFAs). The methods involve precolumn derivatization with 1-naphthylamine and chiral separation on Chiralpak IG-U. anteiso-Methyl branched fatty acids with up to eight carbons can be separated. A method was used for the assignment of the absolute configuration of an aiFA present as fatty acyl residue of the teicoplanin mixture, namely teicoplanin RS3. Furthermore, the excellent methylene selectivity and improved selectivity for constitutional isomers of the polysaccharide columns was exploited for the elucidation and structural confirmation of previously unknown fatty acyl residues in teicoplanin. This shows the versatility and practical applicability of polysaccharide columns as orthogonal stationary phases to reversed-phase for structural elucidation of natural compounds. The developed methods are useful tools for related subdisciplines such as targeted metabolomics and lipidomics. 10.1016/j.jpba.2022.115162
Straight and branched (ω-1)-hydroxylated very long chain fatty acids are components of Bradyrhizobium lipid A. Choma Adam,Komaniecka Iwona Acta biochimica Polonica Lipopolysaccharides of seven Bradyrhizobium strains and three whole-cell fatty acid preparations from bacteria isolated from nodules of Sarothamnus scoparius (common broom) were studied for the presence of very long chain (ω-1)-hydroxy fatty acids. Several such fatty acids were identified. Among them, straight-chain as well as mono- and dimethyl branched acids with chains in the range from 26 to 34 carbon atoms were found. Pyrrolidides and 4,4-dimethyloxazoline derivatives were used to determine the branching position. Carbons at the (ω-10) and/or (ω-11) positions in alkyl chains were points of attachment of methyl groups. These data complete the structure of bradyrhizobial lipid A with important details. The obtained results can be applied in the chemotaxonomy of Bradyrhizobium.
Separation of the fatty acids in menhaden oil as methyl esters with a highly polar ionic liquid gas chromatographic column and identification by time of flight mass spectrometry. Fardin-Kia Ali Reza,Delmonte Pierluigi,Kramer John K G,Jahreis Gerhard,Kuhnt Katrin,Santercole Viviana,Rader Jeanne I Lipids The fatty acids contained in marine oils or products are traditionally analyzed by gas chromatography using capillary columns coated with polyethylene glycol phases. Recent reports indicate that 100 % cyanopropyl siloxane phases should also be used when the analyzed samples contain trans fatty acids. We investigated the separation of the fatty acid methyl esters prepared from menhaden oil using the more polar SLB-IL111 (200 m × 0.25 mm) ionic liquid capillary column and the chromatographic conditions previously optimized for the separation of the complex mixture of fatty acid methyl esters prepared from milk fat. Identifications of fatty acids were achieved by applying Ag(+)-HPLC fractionation and GC-TOF/MS analysis in CI(+) mode with isobutane as the ionization reagent. Calculation of equivalent chain lengths confirmed the assignment of double bond positions. This methodology allowed the identification of 125 fatty acids in menhaden oil, including isoprenoid and furanoid fatty acids, and the novel 7-methyl-6-hexadecenoic and 7-methyl-6-octadecenoic fatty acids. The chromatographic conditions applied in this study showed the potential of separating in a single 90-min analysis, among others, the short chain and trans fatty acids contained in dairy products, and the polyunsaturated fatty acids contained in marine products. 10.1007/s11745-013-3830-2
Fatty acid isomerism: analysis and selected biological functions. Food & function The biological functions of fatty acids and the lipids in which they are esterified are determined by their chain length, double bond position and geometry and other structural motifs such as the presence of methyl branches. Unusual isomeric features in fatty acids of human foods such as conjugated double bonds or chain branching found in dairy products, some seeds and nuts, and marine foods potentially have important effects on human health. Recent advancements in identifying fatty acids with unusual double bond positions and pinpointing the position of methyl branches have empowered the study of their biological functions. We present recent advances in fatty acid structural elucidation by mass spectrometry in comparison with the more traditional methods. The double bond position can be determined by purely instrumental methods, specifically solvent-mediated covalent adduct chemical ionization (SM-CACI) and ozone induced dissociation (OzID), with charge inversion methods showing promise. Prior derivatization using the Paternò-Büchi (PB) reaction to yield stable structures that, upon collisional activation, yield the double bond position has emerged. The chemical ionization (CI) based three ion monitoring (MRM) method has been developed to simultaneously identify and quantify low-level branched chain fatty acids (BCFAs), unattainable by electron ionization (EI) based methods. Accurate identification and quantification of unusual fatty acid isomers has led to research progress in the discovery of biomarkers for cancer, diabetes, nonalcoholic fatty liver disease (NAFLD) and atherosclerosis. Modulation of eicosanoids, weight loss and the health significance of BCFAs are also presented. This review clearly shows that the improvement of analytical capacity is critical in the study of fatty acid biological functions, and stronger coupling of the methods discussed here with fatty acid mechanistic research is promising in generating more refined outcomes. 10.1039/d3fo03716a
Isolation of 2-methyl branched unsaturated very long fatty acids from marine sponge Halichondria panicea and identification of them by GC-MS and NMR. Imbs Andrey B,Rodkina Svetlana A Chemistry and physics of lipids In order to study the biomarker fatty acids of symbionts in the marine sponge Halichondria panicea, purification and structural identification of two new 2-methyl branched monoenoic very long fatty acids (2-Me-24:1 n-7 and 2-Me-26:1 n-9) were performed for the first time. These acids amounted to 7.1% of total sponge FAs, but our attempts to determine their structures by one-step GC-MS analysis were unsuccessful because of low yields of the correspondent N-acyl pyrrolidide derivatives. Silver-ion thin-layer chromatography isolated enriched fractions of monoenoic fatty acids extracted from the sponge. Further purification of unknown fatty acid methyl esters was carried out by reversed-phase high-performance liquid chromatography. Determination of the chain length, degree and position of unsaturations was achieved by gas chromatography-mass spectrometry on methyl esters and dimethyldisulfide adducts. Structures, position of methyl substitution, and double bonds cis isomery were confirmed by 1H nuclear magnetic resonance. 10.1016/j.chemphyslip.2004.01.002
Effects of branched-chain fatty acids on GABA-degradation and behavior: further evidence for a role of GABA in quasi-morphine abstinence behavior. van der Laan J W,Jacobs A W,Bruinvels J Pharmacology, biochemistry, and behavior An increase in GABA-ergic activity has been implicated in the initiation of quasi-morphine abstinence behavior by di-n-propylacetate (DPA). Two structural analogues of DPA, namely, the branched-chain-fatty acid 2-methyl, 2-ethylcaproic acid and 2,2-dimethylvaleric acid have now been used to study this relationship between behavioral and biochemical effects. A correlation appeared to exist between the K1 of these compounds for succinic semi-aldehyde dehydrogenase, the second enzyme in the degradation of GABA, and the doses exerting a maximum effect on behavior. On the other hand concurrent inhibition of GABA-transaminase seemed to suppress the behavioral effects of the fatty acids. This apparent paradox can possibly be explained by supposing a different action of the fatty acids in distinct compartments of the brain, suggesting an important role for increased GABA-ergic activity in the neuronal compartment in the initiation of the quasi-morphine abstinence behavior. 10.1016/0091-3057(80)90217-8
Synthesis and evaluation of radioiodinated terminal p-iodophenyl-substituted alpha- and beta-methyl-branched fatty acids. Goodman M M,Kirsch G,Knapp F F Journal of medicinal chemistry Methods have been developed for the preparation of terminal p-idophenyl-substituted alpha- and beta-methyl-branched long-chain fatty acids. The syntheses and physical properties of 14-(p-iodophenyl)-2(RS)-methyltetradecanoic acid and 15-p-iodophenyl)-3(RS)-methylpentadecanoic acid are described. The radioiodinated agents are of interest as a result of the expected pronounced uptake and prolonged myocardial retention that may result from the inhibition of fatty acid metabolism. Tissue distribution studies in rats with 14-(p-[125I]iodophenyl)-2(RS)-methyltetradecanoic acid and 15-(p-[125I]iodophenyl)-3(RS)-methylpentadecanoic acid show significant heart uptake and prolonged retention accompanied by low in vivo deiodination and high blood levels. A comparison of the heart uptake of the radioiodinated methyl-branched fatty acids and their unbranched analogues has demonstrated a greater myocardial retention of the methyl-branched fatty acids than the unbranched analogues. These results suggest that the mechanism of myocardial retention results from steric or chemical inhibition of the metabolism of these fatty acids by the presence of the methyl group. 10.1021/jm00369a027
Advances in synthetic biology tools paving the way for the biomanufacturing of unusual fatty acids using the Yarrowia lipolytica chassis. Biotechnology advances Unusual fatty acids with special carbon chain length or functional groups have been extensively used in the chemical, material, nutraceutical, and pharmaceutical industries. The traditional sources of these valuable fatty acids mainly include animal or plant extraction and chemical synthesis, which are unsustainable and may cause considerable environmental issues. The advancement of synthetic biology tools has facilitated the microbial production of lipids enriched in these fatty acids. The oleaginous yeast Yarrowia lipolytica is considered an attractive industrial host suitable for the production of advanced unusual fatty acids due to its high intrinsic lipogenesis ability. In this review, we introduce the most cutting-edge developments in synthetic biology tools for Y. lipolytica, as well as the recent progress in harnessing these tools to engineer the Y. lipolytica chassis to overaccumulate various unusual fatty acids, including odd-chain fatty acids, conjugated fatty acids, polyunsaturated fatty acids, cyclopropane fatty acids, methyl-branched fatty acids, hydroxylated fatty acids, and medium chain fatty acids. In addition, the future prospects of the unusual fatty acids using the Y. lipolytica platform are discussed in light of the current progress, challenges, and trends in this field. Finally, guidelines for future studies are also emphasized. 10.1016/j.biotechadv.2022.107984
Branched-chain fatty acids; location of branching methyl groups near carboxyl by rate studies of amide hydrolysis. CASON J,WOLFHAGEN H J The Journal of organic chemistry 10.1021/jo01153a022
Metabolic function of branched-chain volatile fatty acids, growth factors for ruminococci. II. Biosynthesis of higher branched-chain fatty acids and aldehydes. ALLISON M J,BRYANT M P,KATZ I,KEENEY M Journal of bacteriology Allison, M. J. (Dairy Cattle Research Branch, USDA, Beltsville, Md.), M. P. Bryant, I. Katz, and M. Keeney. Metabolic function of branched-chain volatile fatty acids, growth factors for ruminococci. II. Biosynthesis of higher branched-chain fatty acids and aldehydes. J. Bacteriol. 83:1084-1093. 1962.-A number of strains of rumen bacteria require branched-chain volatile fatty acids for growth. A strain of Ruminococcus flavefaciens that requires either isovalerate or isobutyrate incorporates radioactive carbon from isovalerate-1-C(14) and isovalerate-3-C(14) into leucine and into the lipid fraction of the cells. Evidence obtained by both paper and gas chromatography indicated that most of the label in the lipid of cells grown in isovalerate-1-C(14) was in a branched-chain 15-carbon fatty acid, with some in a 17-carbon acid; about 7.5% of the C(14) was recovered in a branched-chain 15-carbon aldehyde. The aldehydes were in the phospholipid fraction and were presumably present as plasmalogen.A strain of R. albus was shown to require isobutyrate, 2-methyl-n-butyrate, or 2-ketoisovalerate for growth. This strain did not incorporate appreciable C(14) from isovalerate-1-C(14) or isovalerate-3-C(14). When grown in a medium containing isobutyrate-1-C(14), most of the cellular C(14) was found in the lipid fraction. Analysis of the lipid demonstrated that the label was present mainly as branched-chain 14-carbon and 16-carbon fatty acids, with 11% of the C(14) present in 14- and 16-carbon carbonyl compounds, presumably branched-chain aldehydes.Branched-chain 14-, 15-, and 16-carbon fatty acids are major components of the lipids of these rumen bacteria. The possibility that these acids and aldehydes, which are found in ruminant body and milk lipids, may be of microbial origin is discussed. 10.1128/jb.83.5.1084-1093.1962
The methyl-branched fortifications of Mycobacterium tuberculosis. Minnikin David E,Kremer Laurent,Dover Lynn G,Besra Gurdyal S Chemistry & biology Mycobacterium tuberculosis continues to be the predominant global infectious agent, annually killing over three million people. Recommended drug regimens have the potential to control tuberculosis, but lack of adherence to such regimens has resulted in the emergence of resistant strains. Mycobacterium tuberculosis has an unusual cell envelope, rich in unique long-chain lipids, that provides a very hydrophobic barrier to antibiotic access. Such lipids, however, can be drug targets, as exemplified by the action of the front-line drug isoniazid on mycolic acid biosynthesis. A number of these lipids are potential key virulence factors and their structures are based on very characteristic methyl-branched long-chain acids and alcohols. This review details the history, structure, and genetic aspects of the biosynthesis of these methyl-branched components, good examples of which are the phthiocerols and the mycocerosic and mycolipenic acids. 10.1016/s1074-5521(02)00142-4
Expansion of the structure-activity relationship of branched chain fatty acids: Effect of unsaturation and branching group size on anticancer activity. Roy Ritik,Roseblade Ariane,Rawling Tristan Chemistry and physics of lipids Branched chain fatty acids (BCFAs) are a class of fatty acid with promising anticancer activity. The BCFA 13-methyltetradecanoic acid (13-MTD) inhibits tumour growth in vivo without toxicity but efficacy is limited by moderate potency, a property shared by all known BCFAs. The mechanism of action of BCFAs has not been fully elucidated, and in the absence of a clearly defined target optimisation of BCFA potency must rely on structure-activity relationships. Our current understanding of the structural features that promote BCFA anticancer activity is limited by the low structural diversity of reported BCFAs.The aim of this study was to examine the effects of two new structural modifications- unsaturation and branching group size- on BCFA activity. Thus, homologous series of saturated and cis-Δ11 unsaturated BCFAs were synthesised bearing methyl, ethyl, propyl and butyl branching groups, and were screened in vitro for activity against three human cancer cell lines. Potencies of the new BCFAs were compared to 13-MTD and an unbranched monounstaurated fatty acid (MUFA) bearing a cis-Δ11 double bond. The principal findings to emerge were that the anticancer activity of BCFAs was adversly affected by larger branching groups but significantly improved by incorporation of a cis-Δ11 double bond into the BCFA alkyl chain. This study provides new structure-activity relationship insights that may be used to develop BCFAs with improved potency and therapeutic potential. 10.1016/j.chemphyslip.2020.104952
Concentrations of volatile 4-alkyl-branched fatty acids in sheep and goat milk and dairy products. Kaffarnik Stefanie,Kayademir Yasemin,Heid Carolina,Vetter Walter Journal of food science Goat and sheep milk and dairy products thereof are characterized by a strong and unique flavor. In this context, the volatile minor fatty acid 4-ethyloctanoic acid plays a prominent role along with 4-methyloctanoic acid when both are present in free form. Using a novel GC/MS method in the selected ion-monitoring mode, previously developed for sheep subcutaneous adipose tissue, we were able to analyze the total concentrations of these flavor-relevant minor fatty acids as methyl esters in goat and sheep milk as well as in their products. Differences between the concentrations and ratios of 4-methyloctanoic acid and 4-ethyloctanoic acid in goat milk (n = 4), goat cheese (n = 4), sheep milk (n = 2), and sheep cheese (n = 4) were observed. Goat milk and cheese resulted in higher concentrations for both fatty acids (190 to 480 μg/g milk fat) and smaller 4-Me-8:0 to 4-Et-8:0 ratios (1.4 to 2.7) compared to sheep milk and cheese (78 to 220 μg/g milk fat; 4-Me-8:0 to 4-Et-8:0 ratio: 15 to 42). In all samples, the concentration of 4-Me-8:0 exceeded the one of 4-Et-8:0. However, due to its lower flavor threshold value the contribution of 4-Et-8:0 to the flavor was generally >76%. The calculated flavor values were >1400 for goat milk and cheeses and >200 for sheep milk and cheeses. In goat milk and its products, only a proportion of <0.1% 4-alkyl-branched fatty acids present in free form in the goat milk and <0.5% in the sheep samples would be sufficient to generate the characteristic goaty flavor. Parameters that promote or prevent the release of 4-Me-8:0, and especially 4-Et-8:0, will be decisive for the flavor in the resulting dairy product. 10.1111/1750-3841.12673
The branched-chain fatty acids of mutton fat. I. The isolation of ( )-14-methyl-hexadecanoic acid. HANSEN R P,SHORLAND F B,COOKE N J The Biochemical journal 10.1042/bj0520203
Structural characterization of saturated branched chain fatty acid methyl esters by collisional dissociation of molecular ions generated by electron ionization. Ran-Ressler Rinat R,Lawrence Peter,Brenna J Thomas Journal of lipid research Saturated branched chain fatty acids (BCFA) are present as complex mixtures in numerous biological samples. The traditional method for structure elucidation, electron ionization (EI) mass spectrometry, sometimes does not unambiguously enable assignment of branching in isomeric BCFA. Zirrolli and Murphy (Zirrolli , J. A. , and R. A. Murphy. 1993. Low-energy tandem mass spectrometry of the molecular ion derived from fatty acid methyl esters: a novel method for analysis of branched-chain fatty acids. J. Am. Soc. Mass Spectrom. 4: 223-229.) showed that the molecular ions of four BCFA methyl ester (BCFAME) yield highly characteristic fragments upon collisional dissociation using a triple quadrupole instrument. Here, we confirm and extend these results by analysis using a tabletop 3-D ion trap for activated molecular ion EI-MS/MS to 30 BCFAME. iso-BCFAME produces a prominent ion (30-100% of base peak) for [M-43] (M-C₃H₇), corresponding to the terminal isopropyl moiety in the original iso-BCFAME. Anteiso-FAME yield prominent ions (20-100% of base peak) corresponding to losses on both side of the methyl branch, [M-29] and [M-57], and tend to produce more prominent m/z 115 peaks corresponding to a cyclization product around the ester. Dimethyl and tetramethyl FAME, with branches separated by at least one methylene group, yield fragment on both sides of the sites of methyl branches that are more than 6 C away from the carboxyl carbon. EI-MS/MS yields uniquely specific ions that enable highly confident structural identification and quantification of BCFAME. 10.1194/jlr.D020651
Tuberculostearic Acid Controls Mycobacterial Membrane Compartmentalization. mBio The intracellular membrane domain (IMD) is a laterally discrete region of the mycobacterial plasma membrane, enriched in the subpolar region of the rod-shaped cell. Here, we report genome-wide transposon sequencing to discover the controllers of membrane compartmentalization in Mycobacterium smegmatis. The putative gene showed the most significant effect on recovery from membrane compartment disruption by dibucaine. Enzymatic analysis of Cfa and lipidomic analysis of a deletion mutant (Δ) demonstrated that Cfa is an essential methyltransferase for the synthesis of major membrane phospholipids containing a C monomethyl-branched stearic acid, also known as tuberculostearic acid (TBSA). TBSA has been intensively studied due to its abundant and genus-specific production in mycobacteria, but its biosynthetic enzymes had remained elusive. Cfa catalyzed the -adenosyl-l-methionine-dependent methyltransferase reaction using oleic acid-containing lipid as a substrate, and Δ accumulated C oleic acid, suggesting that Cfa commits oleic acid to TBSA biosynthesis, likely contributing directly to lateral membrane partitioning. Consistent with this model, Δ displayed delayed restoration of subpolar IMD and delayed outgrowth after bacteriostatic dibucaine treatment. These results reveal the physiological significance of TBSA in controlling lateral membrane partitioning in mycobacteria. As its common name implies, tuberculostearic acid is an abundant and genus-specific branched-chain fatty acid in mycobacterial membranes. This fatty acid, 10-methyl octadecanoic acid, has been an intense focus of research, particularly as a diagnostic marker for tuberculosis. It was discovered in 1934, and yet the enzymes that mediate the biosynthesis of this fatty acid and the functions of this unusual fatty acid in cells have remained elusive. Through a genome-wide transposon sequencing screen, enzyme assay, and global lipidomic analysis, we show that Cfa is the long-sought enzyme that is specifically involved in the first step of generating tuberculostearic acid. By characterizing a deletion mutant, we further demonstrate that tuberculostearic acid actively regulates lateral membrane heterogeneity in mycobacteria. These findings indicate the role of branched fatty acids in controlling the functions of the plasma membrane, a critical barrier for the pathogen to survive in its human host. 10.1128/mbio.03396-22
Branched-chain amino acid catabolism of Thermoanaerobacter pseudoethanolicus reveals potential route to branched-chain alcohol formation. Scully Sean Michael,Orlygsson Johann Extremophiles : life under extreme conditions The fermentation of branched-chain amino acids (BCAAs) to branched-chain fatty acids (BCFAs) and branched-chain alcohols (BCOHs) is described using Thermoanaerobacter pseudoethanolicus. BCAAs were not degraded without an electron scavenging system but were degraded to a mixture of their BCFA (major) and BCOH (minor) when thiosulfate was added to the culture. Various environmental parameters were investigated using isoleucine as the substrate which ultimately demonstrated that at higher liquid-gas phase ratios the formation of 2-methyl-1-butanol from isoleucine achieved a maximal titer of 3.4 mM at a 1:1 liquid-gas ratio suggesting that higher partial pressure of hydrogen influences the BCOH/BCFA ratio but did not increase further with higher L-G phase ratios. Alternately, increasing the thiosulfate concentration decreased the BCOH to BCFA ratio. Kinetic monitoring of BCAA degradation revealed that the formation of BCOHs occurs slowly after the onset of BCFA formation. C2-labeled studies of leucine confirmed the production of a mixture of 3-methyl-1-butyrate and 3-methyl-1-butanol, while experiments involving C1-labeled 3-methyl-1-butyrate in fermentations containing leucine demonstrated that the carboxylic acid is reduced to the corresponding alcohol. Thus, the role of carboxylic acid reduction is likely of importance in the production of BCOH formation during the degradation of BCAA such as leucine. 10.1007/s00792-019-01140-5
Stable carbon isotope ratios of methyl-branched fatty acids are different to those of straight-chain fatty acids in dairy products. Vetter Walter,Gaul Simon,Thurnhofer Saskia,Mayer Kathrin Analytical and bioanalytical chemistry Methyl-branched fatty acids (MBFAs) are the dominant form of fatty acid found in many bacteria. They are also found at low levels in a range of foodstuffs, where their presence has been linked to bacterial sources. In this study we evaluated the potential of compound-specific isotope analysis to obtain insights into the stable carbon isotope ratios (delta(13)C values in per thousand) of individual MBFAs and to compare them to the stable carbon isotope ratios of straight-chain fatty acids in food. Due to their low abundance in foodstuffs, the MBFAs were enriched prior to gas chromatography coupled to isotope ratio mass spectrometric (GC-IRMS) analysis. After transesterification, urea complexation was used to suppress the 16:0 and 18:0 methyl esters that were dominant in the samples. Following that, silver-ion high performance liquid chromatography was used to separate the saturated from the unsaturated fatty acids. The resulting solutions of saturated fatty acids obtained from suet, goat's milk, butter, and human milk were studied by GC-IRMS. The delta(13)C values of fatty acids with 12-17 carbons ranged from -25.4 per thousand to -37.6 per thousand. In all samples, MBFAs were most depleted in carbon-13, followed by the odd-chain fatty acids 15:0 and 17:0. 14:0 and 16:0 contained the highest proportions of carbon-13. The results from this study illustrate that MBFAs have distinctive delta(13)C values and must originate from other sources and/or from very different substrates. These measurements support the initial hypothesis that delta(13)C values can be used to attribute MBFAs to particular sources. 10.1007/s00216-007-1438-1
Branched chain fatty acids; synthesis of acids with branching methyl groups near the carboxyl. CASON J,WOLFHAGEN H J The Journal of organic chemistry 10.1021/jo01153a021
Further studies of the saturated methyl branched fatty acids of vernix caseosa lipid. Nicolaides N,Apon J M Lipids By the method of capillary gas chromatography-mass spectrometry, we have identified 35 monomethyl and 46 dimethyl branched acids in the saturated acids of vernix caseosa lipid with chain lengths ranging from C11 to C18. Many other mono-, di-, and trimethyl branched acids have been partially identified. All methyl branches were found to be on the even numbered C-atoms except for some terminal iso methyl groups. Three types of dimethyl branched acids were found: those with a terminal iso structure, those with a terminal anteiso structure, and those with neither iso nor anteiso structures. The 4-methyl branch predominated for all types of branched acids. Equivalent chain length data for di- and trimethyl branched acids were determined on a Pentasil (nonpopolar) wall coated capillary column and checked by calculation from monomethyl branched acid data. Mass spectral identification was performed with and without the aid of a data system. A possible mode of formation of these acids is discussed.
Xanthomonas campestris FabH is required for branched-chain fatty acid and DSF-family quorum sensing signal biosynthesis. Yu Yong-Hong,Hu Zhe,Dong Hui-Juan,Ma Jin-Cheng,Wang Hai-Hong Scientific reports Xanthomonas campestris pv. campestris (Xcc), a Gram-negative phytopathogenic bacterium, causes black rot disease of cruciferous vegetables. Although Xcc has a complex fatty acid profile comprised of straight-chain fatty acids and branched-chain fatty acids (BCFAs), and encodes a complete set of genes required for fatty acid synthesis, there is still little known about the mechanism of BCFA synthesis. We reported that expression of Xcc fabH restores the growth of Ralstonia solanacearum fabH mutant, and this allows the R. solanacearum fabH mutant to produce BCFAs. Using in vitro assays, we demonstrated that Xcc FabH is able to condense branched-chain acyl-CoAs with malonyl-ACP to initiate BCFA synthesis. Moreover, although the fabH gene is essential for growth of Xcc, it can be replaced with Escherichia coli fabH, and Xcc mutants failed to produce BCFAs. These results suggest that Xcc does not have an obligatory requirement for BCFAs. Furthermore, Xcc mutants lost the ability to produce cis-11-methyl-2-dodecenoic acid, a diffusible signal factor (DSF) required for quorum sensing of Xcc, which confirms that the fatty acid synthetic pathway supplies the intermediates for DSF signal biosynthesis. Our study also showed that replacing Xcc fabH with E. coli fabH affected Xcc pathogenesis in host plants. 10.1038/srep32811
Branched-chain and odd-numbered fatty acids and aldehydes in the nervous system of a patient with deranged vitamin B 12 metabolism. Kishimoto Y,Williams M,Moser H W,Hignite C,Biermann K Journal of lipid research A mixture of isomers of methylhexadecanoic acid was isolated from glycerolipids of brain, spinal cord, and sciatic nerve of a patient who died from methylmalonic aciduria, a disease in which vitamin B(12) is not converted to deoxyadenosyl B(12). The isomers were identified by gas-liquid chromatographic-mass spectrometric analyses, and the data indicated that the points of methyl branching are located predominantly on the even-numbered carbon atoms. The concentration of these branched-chain acids among the glycerolipid fatty acids in the patient's nervous system was at least 0.3-0.9%, while the control tissues contained no more than a trace amount, if any, of these acids. In the spinal cord, these branched acids were distributed among all phosphatides and were in highest concentration on the beta position of phosphatidylcholine. On the other hand, most extraneural tissues contained these acids in much lower concentrations; there were only trace amounts in liver, kidney, muscle, and skin, and 0.2, 0.2, and 0.5% in total ester-linked fatty acids in spleen, duodenum, and lung, respectively. A second abnormality was the 6-13-fold increase in 15:0 and 17:0 fatty acids in all of the glycerolipids in the nervous system of the patient. This abnormality was also observed to a somewhat smaller extent in every extraneural tissue examined. The C(17) aldehydes of phosphatidylethanolamine plasmalogens from the spinal cord of the patient were identified by converting them to the corresponding dimethylacetals. 17:0 dimethylacetal accounted for nearly 10% of total dimethylacetals. There were no abnormalities in total lipids, cholesterol, cerebrosides, and sphingomyelins.
Quantification of branched chain fatty acids in polar and neutral lipids of cheese and fish samples. Hauff Simone,Vetter Walter Journal of agricultural and food chemistry Branched chain fatty acids (iso- and anteiso-fatty acids) are common minor compounds of the lipids found in dairy products and fish (<1-3%) and major fatty acids of Gram-positive bacteria. Their presence in food has been associated with bacterial sources. Bacterial lipids usually consist of polar lipids and virtually no triacylglycerides while food lipids are predominantly composed of triacylglycerides. In this study, we examined the difference in the iso- or anteiso-fatty acid content and composition of neutral and polar lipids in fish and cheese samples. Neutral lipids (triacylglycerides) were separated from the polar lipids (phospholipids) by means of solid-phase extraction (SPE). Deuterium-labeled internal standards were used to verify the successful performance of the accelerated solvent extraction and particularly the SPE. The separated lipid fractions were transformed into their corresponding fatty acid methyl esters, and the concentrations of seven iso- and anteiso-fatty acids were determined by means of gas chromatography coupled to electron ionization mass spectrometry operated in the selected ion monitoring mode (GC/EI-MS-SIM). No coelutions of branched chain fatty acids with other fatty acids were obtained on the medium polar column used for quantification. The branched chain fatty acid content of 17 cheese and 7 fish samples ranged between 0.2% and 1.9% in polar lipids and between 0.1% and 1.7% in neutral lipids. The concentration of total branched chain fatty acids in fish was 2-10 times lower than that found in cheeses, and the relative distribution of iso-17:0 and iso-15:0 increased compared to their anteiso homologues. While branched chain fatty acids in polar lipids of cheese constituted only approximately 1% of the content in total lipids, their contribution in fish was significantly higher (6% to >30%). 10.1021/jf9034805
Enantioseparation and optical rotation of flavor-relevant 4-alkyl-branched fatty acids. Eibler Dorothee,Vetter Walter Journal of chromatography. A Short chain 4-alkyl-branched fatty acids are character impact compounds of the flavor of sheep and goat milk and meat. Due to their methyl or ethyl branches these volatile fatty acids are chiral, and both enantiomers are characterized by different aroma intensities. Recently, it was found that 4-methyloctanoic acid (4-Me-8:0), 4-ethyloctanoic acid (4-Et-8:0), and 4-methylnonanoic acid (4-Me-9:0) are enantiopure in goat and sheep samples, if present. Here we generated enantiopure or enantioenriched standards from racemates by means of (R)-selective esterification with lipase B and verified that 4-Me-8:0, 4-Et-8:0 and 4-Me-9:0 were (R)-enantiopure in these tissues. Determination of the optical rotation and [α] value was carried out to show that (R)-4-Et-8:0 is dextrorotary and to verify the literature values of (R)-4-methyl-branched fatty acids. The elution order of free acids and the methyl and ethyl esters of 4-Me-8:0, 4-Et-8:0, 4-Me-9:0 and 4-methylhexanoic acid (4-Me-6:0) enantiomers was investigated on different chiral columns as well as the (-)-menthyl ester by indirect enantiomer separation on an ionic liquid phase. Different chiral recognition processes were suggested for free acid and esters of 4-Me-8:0 and 4-Me-9:0 on the one hand (decisive: 4-alkyl branch) compared to 4-Me-6:0 on the other hand (decisive: branch on antepenultimate carbon). 10.1016/j.chroma.2017.05.011
Structural basis of branched-chain fatty acid synthesis by Propionibacterium acnes β-ketoacyl acyl Carrier protein synthase. Cheon Dasom,Lee Woo Cheol,Lee Yeongjoon,Lee Jee-Young,Kim Yangmee Biochemical and biophysical research communications Propionibacterium acnes is an anaerobic gram-positive bacterium found in the niche of the sebaceous glands in the human skin, and is a causal pathogen of inflammatory skin diseases as well as periprosthetic joint infection. To gain effective control of P. acnes, a deeper understanding of the cellular metabolism mechanism involved in its ability to reside in this unique environment is needed. P. acnes exhibits typical cell membrane features of gram-positive bacteria, such as control of membrane fluidity by branched-chain fatty acids (BCFAs). Branching at the iso- or anteiso-position is achieved by incorporation of isobutyryl- or 2-methyl-butyryl-CoA via β-ketoacyl acyl carrier protein synthase (KAS III) from fatty acid synthesis. Here, we determined the crystal structure of P. acnes KAS III (PaKAS III) at the resolution of 1.9 Å for the first time. Conformation-sensitive urea polyacrylamide gel electrophoresis and tryptophan fluorescence quenching experiments confirmed that PaKAS III prefers isobutyryl-CoA as the acetyl-CoA, and the unique shape of the active site cavity complies with incorporation of branched-short chain CoAs. The determined structure clearly illustrates how BCFA synthesis is achieved in P. acnes. Moreover, the unique shape of the cavity required for the branched-chain primer can be invaluable in designing novel inhibitors of PaKAS III and developing new specifically targeted antibiotics. 10.1016/j.bbrc.2018.12.134
Design, synthesis, and evaluation of omega-iodovinyl- and omega-iodoalkyl-substituted methyl-branched long-chain fatty acids. Goodman M M,Callahan A P,Knapp F F Journal of medicinal chemistry The synthesis of a new methyl-branched fatty acid, (E)-19-iodo-3(RS)-methyl-18-nonadecenoic acid (19), is described. Methyl branching has been introduced at the 3-position to inhibit beta-oxidation and radioiodide has been attached as a trans-vinyl iodide. Preparation of 19 involved a 15-step sequence of reactions climaxing with formation of the methyl ester 18 by iododestannylation of methyl (E)-19-(tri-n-butylstannyl)-3(RS)-methyl-18-nonadecenoate (17) resulting from the reaction of n-Bu3SnH with methyl 3(RS)-methyl-18-nonadecynoate (16). Methyl branching was introduced at an early stage by Friedel-Crafts acylation of thiophene with 3(RS)-methyl-4-carbomethoxybutanoyl chloride (3) generated from 3-methylglutaric anhydride. The new agent, [125I]-19, showed high myocardial uptake (5 min, 4.89% dose/g; 30 min, 3.32% dose/g), good heart/blood (H/B) ratios (5 min, 5.4/1; 30 min, 4.3/1), and significantly greater myocardial retention in fasted rats than the corresponding straight-chain analogue 19-[125I]-iodo-18-nonadecenoic acid (5 min, 3.52% dose/g, H/B = 4.8/1; 30 min, 1.19% dose/g, H/B = 1.6/1). Excellent myocardial images were obtained in rats after administration of [123I]-19 and confirmed the slow myocardial washout over a 60-min period. These data suggest that 19 is a good candidate for evaluation of heart disease involving aberrations in fatty acid metabolism by use of imaging techniques such as single photon emission computerized tomography (SPECT) where redistribution or washout should be minimized. 10.1021/jm00383a020
BMIPP-design and development. Knapp F F,Kropp J International journal of cardiac imaging In the early 1980s a major obstacle for myocardial SPECT using iodine-123-labeled fatty acids and imaging technology available at that time was the rapid metabolism and myocardial washout of activity. Development of the 15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) fatty acid analogue was based on the established effects of methyl-branching in delineating the enzymatic aberration in Refum's disease and our early studies with the tellurium (Te)-substituted fatty acid analogues. Extensive animal studies with the Te-fatty acids demonstrated that this major structural alteration did not affect initial myocardial extraction, but could successfully inhibit subsequent metabolism and significantly delay washout. Tracer kinetic evaluation and metabolic studies on experimental animals and Langendorff-perfused rat hearts clearly demonstrated that introduction of methyl-branching is an effective approach which alters tracer kinetics by delaying myocardial washout of radioiodinated fatty acids by increasing myocardial retention. Although irreversible retention of iodine-123 BMIPP is not observed, subsequent extensive human studies have clearly substantiated the delayed myocardial washout of BMIPP in comparison with the p-IPPA straight chain analogue. Although contemporary SPECT capabilities allow much more rapid acquisition periods, the delayed washout is still a practical benefit in relation to the use of BMIPP. Most important, the unexpected mis-match which has been widely observed between perfusion tracer distribution and the regional BMIPP distribution (i.e. BMIPP < flow tracer) has been linked to the identification of jeopardized, but viable myocardial regions. In this paper the development of BMIPP is discussed and the results of recent studies focusing on evaluating the effects of the absolute configuration of the branched methyl group using the 3(R)-BMIPP and 3(S)-BMIPP are described. 10.1023/a:1006147228352
A newly identified methyl-branched chain fatty acid synthesizing enzyme from Mycobacterium tuberculosis var. bovis BCG. Fernandes N D,Kolattukudy P E The Journal of biological chemistry Mycobacterium bovis BCG produces a variety of methyl-branched fatty acids. They include C28 to C32 mycocerosic acids esterified to phthiocerol and phenolphthiocerol and the shorter (C22 to C26) mycocerosic acids esterified to phthiocerol. A mycocerosic acid synthase gene-disrupted mutant was still able to produce the shorter mycocerosic acids. The enzyme short chain mycocerosic acid synthase (SMAS), that catalyzes the synthesis of such acids, was purified using anion exchange and red-agarose chromatography. Gel filtration showed the native enzyme to be a 537-kDa protein. Since SDS-polyacrylamide gel electrophoresis of the purified enzyme showed a 280-, 170-, and 100-kDa protein and they cross-reacted with antibodies prepared against the 280- or 100-kDa protein, this enzyme is composed of the three subunits or two 280-kDa monomers with an unusual susceptibility to a proteolytic nick. SMAS utilizes methylmalonyl-CoA with C12 to C20 acyl-CoA as primers and with either NADH or NADPH as the reductant to synthesize the short mycocerosic acids. The Km values for NADH and NADPH were 93 and 90 microM, respectively. Antibodies raised against either the 280- or 100-kDa protein inhibited the incorporation of methylmalonyl-CoA into fatty acids by SMAS. The enzyme is not immunologically closely related to mycocerosic acid synthase or fatty acid synthase. 10.1074/jbc.273.5.2823
Branched Medium Chain Fatty Acids: Iso-Caproate Formation from Iso-Butyrate Broadens the Product Spectrum for Microbial Chain Elongation. Environmental science & technology Chain elongation fermentation can be used to convert organic residues into biobased chemicals. This research aimed to develop a bioprocess for branched medium chain fatty acids (MCFAs) production. A long-term continuous reactor experiment showed that iso-caproate (4-methyl pentanoate, i-C) can be produced via ethanol based chain elongation. The enriched microbiome formed iso-caproate from iso-butyrate at a rate of 44 ± 6 mmol C L day during the last phase. This amounted to 20% of all formed compounds based on carbon atoms. The main fermentation product was n-caproate (55% of all carbon), as a result of acetate and subsequent n-butyrate elongation. The microbiome preferred straight-chain elongation over branched-chain elongation. Lowering the acetate concentration in the influent led to an increase of excessive ethanol oxidation (EEO) into electron equivalents (e.g., H) and acetate. The formed acetate in turn stimulated straight chain elongation, but the resulting lower net acetate supply rate towards straight chain elongation led to an increased selectivity towards and productivity of i-C. The electrons produced via oxidation routes and chain elongation were apparently utilized by hydrogenotrophic methanogens, homoacetogens, and carboxylate-to-alcohol reducing bacteria. Further improvements could be achieved if the acetate-producing EEO was minimized and limitations of ethanol and CO were prevented. 10.1021/acs.est.8b07256
The CoA esters of 2-methyl-branched chain fatty acids and of the bile acid intermediates di- and trihydroxycoprostanic acids are oxidized by one single peroxisomal branched chain acyl-CoA oxidase in human liver and kidney. Vanhove G F,Van Veldhoven P P,Fransen M,Denis S,Eyssen H J,Wanders R J,Mannaerts G P The Journal of biological chemistry Rat liver peroxisomes contain three acyl-CoA oxidases: palmitoyl-CoA oxidase, which oxidizes the CoA esters of straight chain fatty acids and prostaglandins; pristanoyl-CoA oxidase, which oxidizes the CoA esters of 2-methyl-branched fatty acids (e.g. pristanic acid); and trihydroxycoprostanoyl-CoA oxidase, which oxidizes the CoA esters of the bile acid intermediates di- and trihydroxycoprostanic acids (Van Veldhoven, P. P., Vanhove, G., Asselberghs, S., Eyssen, H. J., and Mannaerts, G. P. (1992) J. Biol. Chem. 267, 20065-20074). In the present report we demonstrate that human liver peroxisomes contain only two acyl-CoA oxidases: palmitoyl-CoA oxidase, which oxidizes the CoA esters of straight chain fatty acids and prostaglandins, and a novel branched chain acyl-CoA oxidase, which oxidizes the CoA esters of 2-methyl-branched fatty acids as well as those of the bile acid intermediates (which also possess a 2-methyl substitution in their side chains). The branched chain acyl-CoA oxidase was purified to near homogeneity by means of column chromatography. It appeared to be a 70-kDa monomeric protein that did not cross-react with antisera raised against rat palmitoyl-CoA oxidase and pristanoyl-CoA oxidase. No indication was found for the presence of a separate trihydroxycoprostanoyl-CoA oxidase in human liver. The branched chain acyl-CoA oxidase was present also in human kidney, suggesting that it is expressed in other extrahepatic tissues as well. Our results explain a number of clinical-chemical observations made in certain cases of peroxisomal beta-oxidation disorders.
ECHDC1 knockout mice accumulate ethyl-branched lipids and excrete abnormal intermediates of branched-chain fatty acid metabolism. Dewulf Joseph P,Paquay Stéphanie,Marbaix Etienne,Achouri Younès,Van Schaftingen Emile,Bommer Guido T The Journal of biological chemistry The cytosolic enzyme ethylmalonyl-CoA decarboxylase (ECHDC1) decarboxylates ethyl- or methyl-malonyl-CoA, two side products of acetyl-CoA carboxylase. These CoA derivatives can be used to synthesize a subset of branched-chain fatty acids (FAs). We previously found that ECHDC1 limits the synthesis of these abnormal FAs in cell lines, but its effects in vivo are unknown. To further evaluate the effects of ECHDC1 deficiency, we generated knockout mice. These mice were viable, fertile, showed normal postnatal growth, and lacked obvious macroscopic and histologic changes. Surprisingly, tissues from wild-type mice already contained methyl-branched FAs due to methylmalonyl-CoA incorporation, but these FAs were only increased in the intraorbital glands of ECHDC1 knockout mice. In contrast, ECHDC1 knockout mice accumulated 16-20-carbon FAs carrying ethyl-branches in all tissues, which were undetectable in wild-type mice. Ethyl-branched FAs were incorporated into different lipids, including acylcarnitines, phosphatidylcholines, plasmanylcholines, and triglycerides. Interestingly, we found a variety of unusual glycine-conjugates in the urine of knockout mice, which included adducts of ethyl-branched compounds in different stages of oxidation. This suggests that the excretion of potentially toxic intermediates of branched-chain FA metabolism might prevent a more dramatic phenotype in these mice. Curiously, ECHDC1 knockout mice also accumulated 2,2-dimethylmalonyl-CoA. This indicates that the broad specificity of ECHDC1 might help eliminate a variety of potentially dangerous branched-chain dicarboxylyl-CoAs. We conclude that ECHDC1 prevents the formation of ethyl-branched FAs and that urinary excretion of glycine-conjugates allows mice to eliminate potentially deleterious intermediates of branched-chain FA metabolism. 10.1016/j.jbc.2021.101083
Cuticular hydrocarbons of triatomines. Juárez M P,Fernández G C Comparative biochemistry and physiology. Part A, Molecular & integrative physiology Triatomine insects (Hemiptera) are the vectors of Chagas disease. Their cuticular surface is covered by a thin layer of lipids, mainly hydrocarbons, wax esters, fatty alcohols, and free or esterified fatty acids. These lipids play a major role in preventing a lethal desiccation, altering the absorption of chemicals and microorganism penetration, they also participate in chemical communication events. Lipid components are biosynthetically related, the synthesis of long chain and very long chain fatty acids was first shown in the integument of Triatoma infestans through the concerted action of fatty acid synthases (FAS's) and fatty acyl-CoA elongases. A final decarboxylation step produces the corresponding hydrocarbon. Capillary gas chromatography coupled to mass spectrometry analyses showed that cuticular hydrocarbons of Triatominae comprise saturated straight and methyl-branched chains, from 18 to more than 43 carbon atoms. Odd-chain hydrocarbons, mostly from 27 to 33 carbons, are the major straight chains. Different isomers of mono, di, tri, and tetramethylcomponents, mostly from 29 to 39 atoms in the carbon skeleton, account for the major methyl-branched hydrocarbons. The presence, absence, and relative quantities of these hydrocarbons represent characters for their chemical phenotype, and are useful for differentiating genera, species and populations. In this review, we will discuss the metabolic pathways involved in hydrocarbon formation, and their structure, together with their role in insect survival. We will also review the utility of cuticular hydrocarbon fingerprints in chemotaxonomy. 10.1016/j.cbpa.2006.08.031
Cistus ladanifer L. Shrub is Rich in Saturated and Branched Chain Fatty Acids and their Concentration Increases in the Mediterranean Dry Season. Guerreiro Olinda,Alves Susana P,Duarte Maria F,Bessa Rui J B,Jerónimo Eliana Lipids The Cistus ladanifer L. shrub is a widespread species of the Mediterranean region that is available as a feed source for ruminants all the year round, constituting a source of energy and nutrients when most of the vegetation is dry. However, there is no trustworthy information about the fatty acid composition of C. ladanifer, as well as no information about the seasonal and age related changes in their fatty acid composition. Thus, we collected the aerial parts of C. ladanifer plants of two age groups [young vs. older ones (2-6 years old)] during four consecutive seasons to characterize their fatty acid composition. The fatty acid composition of C. ladanifer is dominated by saturated fatty acids including the occurrence of two methyl branched chain fatty acids (BCFA), the iso-19:0 and iso-21:0, which as far as we know were detected for the first time in shrubs. Also, we demonstrated that several labdane type compounds might interfere with the fatty acid analysis of C. ladanifer. Marked seasonal changes in BCFA and polyunsaturated fatty acids (PUFA) were found, suggesting that BCFA can replace PUFA in plant lipids at high environmental temperatures. 10.1007/s11745-015-4001-4
Direct determination of flavor relevant and further branched-chain fatty acids from sheep subcutaneous adipose tissue by gas chromatography with mass spectrometry. Kaffarnik Stefanie,Preuß Siegfried,Vetter Walter Journal of chromatography. A 4-Methyloctanoic acid, 4-ethyloctanoic acid and 4-methylnonanoic acid are key-flavor compounds of sheep and goat. Yet, the low amounts of these volatile branched-chain fatty acids (vBCFAs) in the fat of the ruminants hampered their determination on a routine basis. In this work we developed a gas chromatography/mass spectrometry selected ion monitoring (GC/MS-SIM) method for the direct determination of the vBCFAs as methyl esters, which were obtained after transesterification of subcutaneous adipose tissue of sheep. The excellent sensitivity of the GC/MS-SIM method (limit of quantification, LOQ, 3.6-4.8μg/g; limit of detection, LOD, 1.1-1.4μg/g for 4-Me-8:0, 4-Et-8:0 and 4-Me-9:0) enabled us to determine the three vBCFAs without an enrichment step. Subcutaneous adipose sheep tissue of three different breeds contained 23-88μg/g 4-methyloctanoic acid, 13-26μg/g 4-ethyloctanoic acid and ∼2.9-18μg/g 4-methylnonanoic acid. Since all fatty acids were present in the FAME fraction, the samples could be screened for further branched-chain FAMEs. After elimination of unsaturated fatty acids by hydrogenation (the presence of some unsaturated fatty acids could be verified by this measure), additional measurements in SIM and full scan modes of methyl esters and picolinyl esters enabled the determination of further 97 saturated fatty acids in the samples with eight to 20 carbons. The method is suited for routine analysis and may be useful to investigate the reasons for the abundance/absence of 4-methyloctanoic acid, 4-ethyloctanoic acid and 4-methylnonanoic acid and further branched-chain fatty acids in sheep and goat. 10.1016/j.chroma.2014.05.034
New branched-chain fatty acids from the Senegalese gorgonian Leptogorgia piccola (white and yellow morphs). Mirallès J,Barnathan G,Galonnier R,Sall T,Samb A,Gaydou E M,Kornprobst J M Lipids Fatty acids from total lipids of the gorgonian Leptogorgia piccola (white and yellow morphs), collected from the same area at two different periods with regard to the average water temperature, were studied. More than fifty fatty acids were identified as methyl esters and N-acyl pyrrolidides by gas chromatography and gas chromatography/mass spectrometry. Three new, branched-chain unsaturated fatty acids were identified in addition to the unusual 7-methyl-6-hexadecenoic acid, namely 10-methyl-6-hexadecenoic, 7,9-dimethyl-6-hexadecenoic, and 10-methyl-6,9-heptadecadienoic acids. Also 6,9-heptadecadienoic acid was identified. The fatty acid patterns of specimens harvested in colder waters were quite different from those harvested in warmer waters in that the former contained high amounts of methylene-interrupted polyunsaturated acids, including tetracosapolyenoic acids, especially 6,9,12,15,18-24:5 (up to 15.8% of the total acid mixture) and 6,9,12,15,18,21-24:6 (up to 5.3%). Arachidonic acid was, nevertheless, a major component in all the fatty acid mixtures studied (13.6-20.5%). Based on gas chromatography/Fourier transform infrared experiments, the double bonds were assigned the (Z) configuration. Several fatty aldehydes and their dimethyl acetals were also detected, of which the most abundant was octadecanal.
Identification of methyl-branched fatty acids from the triacylglycerols of subcutaneous adipose tissue of lambs. Smith A,Calder A G,Lough A K,Duncan W R Lipids A concentrate of branched chain fatty acids (as methyl esters) was prepared from the triacylglycerols of subcutaneous adipose tissue lipids of lambs receiving a carbohydrate-rich (cereal diet). This was accomplished by procedures which allowed the removal of unsaturated components by peroxidation and straight chain saturated components by urea-adduct formation. The concentrate was analyzed by high resolution gas chromatography in combination with mass spectrometry and was shown to consist of a complex mixture of saturated methyl-substituted fatty acids. Methyl substitution occurred on even-numbered carbon atoms (relative to the carboxyl group) and the chain lengths of the acids ranged from 10 to 18 carbon atoms. Acids with one methyl substituent in the fatty acyl chain were most abundant; di-, tri- and tetramethyl-substituted acids were also present. The biosynthesis of these methyl-substituted acids is discussed briefly.
Characterization of branched-chain fatty acids from fallow deer perinephric triacylglycerols by gas chromatography-mass spectrometry. Smith A,Duncan W R Lipids Branched-chain fatty acids of perinephric triacylglycerols of semi-feral fallow deer (Dama dama dama) were analyzed by high resolution gas chromatography-mass spectrometry. Of the total fatty acids, 15.50% were Branched-chain components including 8.96% iso acids, mostly 14-methylpentacanoic acid, 2.85% anteiso acids and 1.73% of other monomethyl-substituted acids; dimethyl-branched acids with an iso structure (1.05%) and with an anteiso structure (0.18%) were also present. Whereas the predominant iso acids and methyl-substituted iso acids had chain lengths of 13 and 15 carbon atoms, the anteiso acids and methyl-substituted anteiso acids had chain lengths of 14 and 16 carbon atoms. Methyl substitution occurred on the even numbered carbon atoms relative to the carboxyl group. The general composition is also given of the fatty acids comprising the triacylglycerols of subcutaneous (rump area) and perinephric adipose tissue.
Radioiodinated branched-chain fatty acids: substrates for beta oxidation? Concise communication. Otto C A,Brown L E,Scott A M Journal of nuclear medicine : official publication, Society of Nuclear Medicine Branched-chain iodinated fatty acids have been proposed for use as myocardial imaging agents. Several omega- iodoalkyl and omega- iodoaryl beta-methyl branched fatty acids have been synthesized and tested in rats. Myocardial activity levels at t = 5 min are affected by chain length for both alkyl and aryl acids, with chain lengths of 16 carbons possessing higher levels of activity than shorter lengths. Branching significantly lowers heart-to-blood ratios relative to straight-chain analogs. The degree of branching also affects radioactivity levels. Monoalkylation at the beta-carbon does not reduce the levels for omega- iodoalkyl fatty acids, but dialkylation reduces the levels significantly. Branching in the omega- iodoaryl series of fatty acids altered the time course of activity in the myocardium from a level of activity decreasing with time for the straight-chain acid to an essentially constant level of activity for the branched analogs.
S-methyl thioesters are produced from fatty acids and branched-chain amino acids by brevibacteria: focus on L-leucine catabolic pathway and identification of acyl-CoA intermediates. Sourabié Alain M,Spinnler Henry-Eric,Bourdat-Deschamps Marjolaine,Tallon Richard,Landaud Sophie,Bonnarme Pascal Applied microbiology and biotechnology Despite their importance as potent odors that contribute to the aroma of numerous cheeses, S-methyl thioesters formation pathways have not been fully established yet. In a first part of our work, we demonstrated that Brevibacterium antiquum and Brevibacterium aurantiacum could produce S-methyl thioesters using short-chain fatty acids or branched-chain amino acids as precursors. Then, we focused our work on L-leucine catabolism using liquid chromatography tandem mass spectrometry and gas chromatography-mass spectrometry analyses coupled with tracing experiments. For the first time, several acyl-CoAs intermediates of the L-leucine to thioesters conversion pathway were identified. S-methyl thioisovalerate was produced from L-leucine, indicating that this amino acid was initially transaminated. Quite interestingly, data also showed that other S-methyl thioesters, e.g., S-methyl thioacetate or S-methyl thioisobutyrate, were produced from L-leucine. Enzymatic and tracing experiments allowed for postulating catabolic pathways leading to S-methyl thioesters biosynthesis. 10.1007/s00253-011-3500-3
Fatty Acids from a Glass Sponge Aulosaccus sp. Occurrence of New Cyclopropane-Containing and Methyl-Branched Acids. Santalova Elena A,Denisenko Vladimir A Lipids In order to identify new structures, the free fatty acids from an extract of a glass sponge Aulosaccus sp. (from the north-west Pacific) belonging to one of the least chemically investigated classes (Hexactinellida), were fractionated by RP-HPLC and analyzed by NMR spectroscopy and GC-MS of their pyrrolidine derivatives, methyl(ethyl) esters and their dimethyl disulfide adducts. One hundred and twenty-three C-C acids (including nine new compounds) were detected, one hundred and ten of these compounds have not been found previously in glass sponges. The levels of common methylene-interrupted polyenes, monoenes of the (n-7) family and less common branched-chain components proved to be high. New acids were shown to be 5,13-dimethyl-tetradec-4-enoic, cis-10,11-methylene-heptadecanoic, 10,12-dimethyl-octadecanoic, cis-12,13-methylene-nonadecanoic, (14E)-13-methyl-eicos-14-enoic, 19-methyl-eicos-13-enoic, cis-20,21-methylene-heptacosanoic, 27-methyl-octacos-21-enoic and (22Z)-nonacos-22-enoic. Some important mass spectrometric characteristics of pyrrolidides of homologous cyclopropane fatty acids are reported and discussed. 10.1007/s11745-016-4214-1
Inactivation of the peroxisomal multifunctional protein-2 in mice impedes the degradation of not only 2-methyl-branched fatty acids and bile acid intermediates but also of very long chain fatty acids. Baes M,Huyghe S,Carmeliet P,Declercq P E,Collen D,Mannaerts G P,Van Veldhoven P P The Journal of biological chemistry According to current views, peroxisomal beta-oxidation is organized as two parallel pathways: the classical pathway that is responsible for the degradation of straight chain fatty acids and a more recently identified pathway that degrades branched chain fatty acids and bile acid intermediates. Multifunctional protein-2 (MFP-2), also called d-bifunctional protein, catalyzes the second (hydration) and third (dehydrogenation) reactions of the latter pathway. In order to further clarify the physiological role of this enzyme in the degradation of fatty carboxylates, MFP-2 knockout mice were generated. MFP-2 deficiency caused a severe growth retardation during the first weeks of life, resulting in the premature death of one-third of the MFP-2(-/-) mice. Furthermore, MFP-2-deficient mice accumulated VLCFA in brain and liver phospholipids, immature C(27) bile acids in bile, and, after supplementation with phytol, pristanic and phytanic acid in liver triacylglycerols. These changes correlated with a severe impairment of peroxisomal beta-oxidation of very long straight chain fatty acids (C(24)), 2-methyl-branched chain fatty acids, and the bile acid intermediate trihydroxycoprostanic acid in fibroblast cultures or liver homogenates derived from the MFP-2 knockout mice. In contrast, peroxisomal beta-oxidation of long straight chain fatty acids (C(16)) was enhanced in liver tissue from MFP-2(-/-) mice, due to the up-regulation of the enzymes of the classical peroxisomal beta-oxidation pathway. The present data indicate that MFP-2 is not only essential for the degradation of 2-methyl-branched fatty acids and the bile acid intermediates di- and trihydroxycoprostanic acid but also for the breakdown of very long chain fatty acids. 10.1074/jbc.M001994200
Branched-chain fatty acids promote Listeria monocytogenes intracellular infection and virulence. Sun Yvonne,O'Riordan Mary X D Infection and immunity Anteiso-branched-chain fatty acids (BCFA) represent the dominant group of membrane fatty acids and have been established as crucial determinants in resistance against environmental stresses in Listeria monocytogenes, a facultative intracellular pathogen. Here, we investigate the role of anteiso-BCFA in L. monocytogenes virulence by using mutants deficient in branched-chain alpha-keto acid dehydrogenase (BKD), an enzyme complex involved in the synthesis of BCFA. In tissue culture models of infection, anteiso-BCFA contributed to intracellular growth and survival in macrophages and significantly enhanced plaque formation upon prolonged infection in L2 fibroblasts. The intracellular defects observed could be attributed partially to insufficient listeriolysin O (LLO) production, indicating a requirement for anteiso-BCFA in regulating virulence factor production. In a murine model of infection, the BKD-deficient mutant was highly attenuated, further emphasizing the importance of BKD-mediated metabolism in L. monocytogenes virulence. This study demonstrates an underappreciated role for BCFA in bacterial pathogenesis, which may provide insight into the development and application of antimicrobial agents. 10.1128/IAI.00546-10
[Peroxisomal beta-oxidation]. Mannaerts G P,Van Veldhoven P P Verhandelingen - Koninklijke Academie voor Geneeskunde van Belgie In animal cells peroxisomes as well as mitochondria are capable of degrading lipids via beta-oxidation. Nevertheless, there are important differences between the two systems. 1) The peroxisomal and mitochondrial beta-oxidation enzymes are different proteins. 2) Peroxisomal beta-oxidation does not degrade fatty acids completely but acts as a chain-shortening system, catalyzing only a limited number of beta-oxidation cycles. 3) Peroxisomal beta-oxidation is not coupled to oxidative phosphorylation and is thus less efficient than mitochondrial beta-oxidation as far as energy conservation is concerned. 4) Peroxisomal beta-oxidation is not regulated by malonyl-CoA and--as a consequence--by feeding as opposed to starvation. Peroxisomes are responsible for the beta-oxidation of very long chain (> C20) fatty acids, dicarboxylic fatty acids, 2-methyl-branched fatty acids, prostaglandins, leukotrienes, and the carboxyl side chains of certain xenobiotics and of the bile acid intermediates di- and trihydroxycoprostanic acids. Mitochondria oxidize mainly long (C16-C20) chain fatty acids, which--because of their abundance--constitute a major source of metabolic fuel. The first step in peroxisomal beta-oxidation is catalyzed by two acyl-CoA oxidases in extrahepatic tissues and by three acyl-CoA oxidases in liver, each enzyme having its own substrate specificity. Palmitoyl-CoA oxidase and pristanoyl-CoA oxidase are found in liver and extrahepatic tissues. The former enzyme oxidizes the CoA esters of straight chain fatty acids, dicarboxylic fatty acids and prostaglandins; the latter enzyme oxidizes the CoA esters of branched fatty acids but also shows some activity towards straight chain and dicarboxylic fatty acids. Hepatic peroxisomes contain a third acyl-CoA oxidase, trihydroxycoprostanoyl-CoAA oxidase, which oxidizes the CoA esters of the bile acid intermediates di- an trihydroxycoprostanic acids. Treatment of rodents with a number of structurally diverse compounds called peroxisome proliferators, results in the proliferation of peroxisomes, especially in liver, and in the induction of the hepatic peroxisomal beta-oxidation enzymes except pristanoyl-CoA oxidase and trihydroxycoprostanoyl-CoA oxidase. There exist several inborn errors, in which peroxisomal beta-oxidation is deficient. These diseases are characterized by severe neurological symptoms. The biochemical findings in these diseases confirm the function of peroxisomal beta-oxidation as described above.
Fatty acid composition of caprine milk: major, branched-chain, and trans fatty acids. Alonso L,Fontecha J,Lozada L,Fraga M J,Juárez M Journal of dairy science The fatty acid composition of caprine milk fat was studied using capillary gas chromatography. Milk was obtained from five goat herds belonging to different breeders in the Murcia region (Spain) and collected monthly (from November to May). The results showed significant differences among herds mainly in long-chain fatty acids (C16:0, C18:0, and C18:2). There were five branched-chain fatty acids (iso- and anteiso-C15:0, iso- and anteiso-C17:0, and iso-C16:0) with > 0.1% of the total fatty acid methyl esters and another 31 (the most monomethylated) with < 0.1%, including 4-ethyloctanoate, which is implicated in goat-like flavors. To study the content of trans unsaturated fatty acids, the fatty acid methyl esters were previously fractionated by AgNO3-thin layer chromatography. The mean contents of trans-C16:1 and trans-C18:1 were 0.16 and 2.12%, respectively. The distribution profile of trans-C18:1 was also studied. 10.3168/jds.S0022-0302(99)75306-3
Branched chain fatty acids in phospholipids of guinea pig Harderian gland. Seyama Y,Ohashi K,Imamura T,Kasama T,Otsuka H Journal of biochemistry Fatty acid compositions of phosphatidyl ethanolamine and phosphatidyl choline extracted from the guinea pig Harderian gland were examined by gas chromatography and gas chromatography-mass spectrometry. Oleic acid was the major component of both phospholipids, but a large amount of saturated branched chain fatty acids was found: 34.5% in phosphatidyl ethanolamine, and 42.9% in phosphatidyl choline. On the other hand, linolenic and arachidonic acids were not found in these phospholipids. At the 1-position of phosphatidyl choline and phosphatidyl ethanolamine, 54.3% and 40.9% of fatty acids, respectively, had methyl branches. These methyl branches were located at the even-numbered carbon atoms. Branched chain fatty acids were also found at the 2-position of both lipids: 36.2% in phosphatidyl choline and 31.2% in phosphatidyl ethanolamine. The fatty acids of phosphatidyl ethanolamine and phosphatidyl choline from liver, cerebrum, cerebellum, erythrocytes, and plasma of the same animal were also analyzed. Saturated and unsaturated fatty acids, including arachidonic acid, were the major components. Branched chain fatty acids were also found in these lipids, but in very small amounts. 10.1093/oxfordjournals.jbchem.a134468
Carnitine--metabolism and functions. Bremer J Physiological reviews Carnitine was detected at the beginning of this century, but it was nearly forgotten among biochemists until its importance in fatty acid metabolism was established 50 years later. In the last 30 years, interest in the metabolism and functions of carnitine has steadily increased. Carnitine is synthesized in most eucaryotic organisms, although a few insects (and most likely some newborn animals) require it as a nutritional factor (vitamin BT). Carnitine biosynthesis is initiated by methylation of lysine. The trimethyllysine formed is subsequently converted to butyrobetaine in all tissues; the butyrobetaine is finally hydroxylated to carnitine in the liver and, in some animals, in the kidneys (see Fig. 1). It is released from these tissues and is then actively taken up by all other tissues. The turnover of carnitine in the body is slow, and the regulation of its synthesis is still incompletely understood. Microorganisms (e.g., in the intestine) can metabolize carnitine to trimethylamine, dehydrocarnitine (beta-keto-gamma-trimethylaminobutyric acid), betaine, and possibly to trimethylaminoacetone. In some insects carnitine can be converted to methylcholine, presumably with trimethylaminoacetone as an intermediate (see Fig. 3). In mammals the unphysiological isomer (+) carnitine is converted to trimethylaminoacetone. The natural isomer (-)carnitine is excreted unchanged in the urine, and it is still uncertain if it is degraded in mammalian tissues at all (Fig. 2). The only firmly established function of carnitine is its function as a carrier of activated fatty acids and activated acetate across the inner mitochondrial membrane. Two acyl-CoA:carnitine acyltransferases with overlapping chain-length specificities have been isolated: one acetyltransferase taking part in the transport of acetyl and short-chain acyl groups and one palmitoyltransferase taking part in the transport of long-chain acyl groups. An additional octanoyltransferase has been isolated from liver peroxisomes. Although a carnitine translocase that allows carnitine and acylcarnitine to penetrate the inner mitochondrial membrane has been deduced from functional studies (see Fig. 5), this translocase has not been isolated as a protein separate from the acyltransferases. Carnitine acetyltransferase and carnitine octanoyltransferase are also found in the peroxisomes. In these organelles the enzymes may be important in the transfer of acyl groups, which are produced by the peroxisomal beta-oxidation enzymes, to the mitochondria for oxidation in the citric acid cycle. The carnitine-dependent transport of activated fatty acids across the mitochondrial membrane is a regulated process. Malonyl-CoA inh 10.1152/physrev.1983.63.4.1420
Separation and identification of diacylglycerols containing branched chain fatty acids by liquid chromatography-mass spectrometry. Palyzová Andrea,Řezanka Tomáš Journal of chromatography. A A combination of two chromatographic and two enzymatic methods was used for the analysis of molecular species of lipids from Gram-positive bacteria of the genus Kocuria. Gram-positive bacteria contain a majority of branched fatty acids (FAs), especially iso- and/or anteiso-FAs. Two strains K. rhizophila were cultivated at three different temperatures (20, 28, and 37°C) and the majority phospholipid, i.e., the mixture of molecular species of phosphatidylglycerols (PGs) was separated by means of hydrophilic interaction liquid chromatography (HILIC). After enzymatic hydrolysis of PGs by phospholipase C and derivatization of the free OH group, the sn-1,2-diacyl-3-acetyl triacylglycerols (AcTAGs) were separated by reversed phase HPLC. Molecular species such as i-15:0/i-15:0/2:0, ai-15:0/ai-15:0/2:0, and 15:0/15:0/2:0 (straight chains) were identified by liquid chromatography-positive electrospray ionization mass spectrometry. The tandem mass spectra of both standards and natural compounds containing iso, anteiso and straight chain FAs with the same carbons were identical. Therefore, for identification of the ratio of two regioisomers, i.e. i-15:0/ai-15:0/2:0 vs. ai-15:0/i-15:0/2:0, they were cleavage by pancreatic lipase. The mixture of free fatty acids (FFAs) and 2-monoacylglycerols (2-MAGs) was obtained. After their separation by TLC and esterification and/or transesterification, the fatty acid methyl esters were quantified by GC-MS and thus the ratio of regioisomers was determined. It has been shown that the ratio of PG (containing as majority i-15: 0 / i-15: 0, i-15: 0 / ai-15: 0 and / or ai-15: 0 / i-15: 0 and ai-15: 0 / ai-15: 0 molecular species) significantly affected the membrane flow of bacterial cells cultured at different temperatures. 10.1016/j.chroma.2020.461708
Inactivation of Gram-Positive Bacteria by Novel Phenolic Branched-Chain Fatty Acids. Journal of food protection Novel phenolic branched-chain fatty acids (PBC-FAs) were evaluated for their antimicrobial properties against both gram-positive ( Listeria innocua , Bacillus subtilis , Enterococcus faecium ) and gram-negative ( Escherichia coli , Salmonella Typhimurium, and Pseudomonas tolaasii ) bacteria. In addition, PBC-FA derivatives, such as PBC-FA methyl ester mixture, methyl-branched fatty acid mixtures, and trimethylsilyl-PBC-FA methyl esters, were synthesized to study the structure activity relationship. Results showed that PBC-FAs were a potent antimicrobial against gram-positive bacteria with MICs of 1.8 to 3.6 μg/ml. The compounds were less effective against gram-negative bacteria. Derivatives of PBC-FAs and an equimolar mixture of oleic acid and phenol all had MICs above 233 μg/ml against both gram-positive and gram-negative bacteria. Comparison of antimicrobial activities of the PBC-FAs with those of the derivatives suggests that the carboxylic group in the fatty acid moiety and the hydroxyl group on the phenol moiety were responsible for the antimicrobial efficacy. Growth curves of L. innocua revealed that PBC-FAs prevented bacterial growth, while MBC-FAs only delayed the onset of rapid growth of L. innocua . Our results demonstrated that the novel PBC-FAs have potential for use as antimicrobials against gram-positive bacteria. 10.4315/0362-028X.JFP-16-080
Peroxisomal beta-oxidation of branched chain fatty acids in human skin fibroblasts. Singh H,Brogan M,Johnson D,Poulos A Journal of lipid research Human skin fibroblasts in suspension are able to degrade [1-14C]-labeled alpha- and gamma-methyl branched chain fatty acids such as pristanic and homophytanic acid. Pristanic acid was converted to propionyl-CoA, whereas homophytanic acid was beta-oxidized to acetyl-CoA. Incubation of skin fibroblasts with [1-14C]-labeled fatty acids for longer periods produced radiolabeled carbon dioxide, presumably by further degradation of acetyl-CoA or propionyl-CoA generated by beta-oxidation. Under the same conditions similar products were produced from very long chain fatty acids, such as lignoceric acid. Inclusion of digitonin (> 10 micrograms/ml) in the incubations strongly inhibited carbon dioxide production but stimulated acetyl-CoA or propionyl-CoA production from fatty acids. ATP, Mg2+, coenzyme A, NAD+ and L-carnitine stimulated acetyl-CoA or propionyl-CoA production from [1-14C]-labeled fatty acids in skin fibroblast suspensions. Branched chain fatty acid beta-oxidation was reduced in peroxisome-deficient cells (Zellweger syndrome and infantile Refsum's disease) but they were beta-oxidized normally in cells from patients with X-linked adrenoleukodystrophy (ALD). Under the same conditions, lignoceric acid beta-oxidation was impaired in the above three peroxisomal disease states. These results provide evidence that branched chain fatty acid, as well as very long chain fatty acid, beta-oxidation occurs only in peroxisomes. As the defect in X-linked ALD is in a peroxisomal fatty acyl-CoA synthetase, which is believed to be specific for very long chain fatty acids, we postulate that different synthetases are involved in the activation of branched chain and very long chain fatty acids in peroxisomes.
Long-chain multiple methyl-branched fatty acid-containing lipids of Mycobacterium tuberculosis: biosynthesis, transport, regulation and biological activities. Jackson Mary,Stadthagen Gustavo,Gicquel Brigitte Tuberculosis (Edinburgh, Scotland) The cell envelope of pathogenic mycobacteria is highly distinctive in that it contains a number of lipids esterified with structurally related long-chain multi-methyl-branched fatty acids. These lipids have long been thought to play important roles in the cell envelope structure as well as in the pathogenicity of the tubercle bacillus. This review summarizes what is known about the biosynthesis of long-chain multiple methyl-branched fatty acid-containing lipids in Mycobacterium tuberculosis and describes the most recent findings about their regulation, transport across the different layers of the cell envelope and their biological functions. 10.1016/j.tube.2006.05.003
Structural Identification of Monounsaturated Branched Chain Fatty Acid Methyl Esters by Combination of Electron Ionization and Covalent Adduct Chemical Ionization Tandem Mass Spectrometry. Wang Zhen,Wang Dong Hao,Park Hui Gyu,Tobias Herbert J,Kothapalli Kumar S D,Brenna J Thomas Analytical chemistry Monounsaturated fatty acids (-MUFA) and saturated branched chain fatty acids (BCFA) are structurally characterized by separate tandem mass spectrometry methods for double bond localization and for chain branching in their respective fatty acid methyl ester (FAME) derivatives; however, these methods have never been applied to branched monounsaturated FAME. Here, we report application of electron ionization (EI)-MS/MS and solvent-mediated covalent adduct chemical ionization (CACI)-MS/MS of monounsaturated BCFA methyl esters (MUBCFAME) of a chain length of 15-20 carbons. A novel system was used to implement CI with low vapor pressure reagents in a tabletop triple quadrupole MS. -MUBCFA EI-MS/MS of the molecular ion (M) yields a characteristic diagnostic ion [M-29]. -MUBCFA can be distinguished from -MUFA by an ion intensity ratio of [M-32]/[M-43], with -MUBCFA yielding a ratio greater than 1.7, while -MUFA yields a ratio less than 1.0. Chain branching at the and positions, terminal isopropyl and -butyl, respectively, do not alter CACI-MS/MS diagnostic ions compared to normal BCFA, enabling double bond positions of MUBCFA to be determined with the analogous α and ω diagnostic ions from cleavage on both sides of the erstwhile double bond. Taken together, this straightforward FAME-based technique via combination of EI-MS/MS and CACI-MS/MS enables fundamental structural identification of MUBCFA without standards. 10.1021/acs.analchem.9b03912
Distribution of volatile branched-chain fatty acids in various lamb tissues. Brennand C P,Lindsay R C Meat science Volatile fatty acids (C4-C11) including even-, odd-, and branched-chain members in lamb tissues were quantitatively analyzed. Volatile branched-chain fatty acids (BCFA) were more concentrated in subcutaneous adipose tissue samples (rump, shoulder, breast) than in perinepheric adipose or muscle tissues. Perinepheric adipose tissue contained relatively high quantities of n-chain, even-numbered fatty acids and very low levels of BCFA. Greater variation existed in fatty acid profiles among similar subcutaneous adipose tissues from different lambs than between samples of adipose tissue from different carcass sites from a given lamb sample. 4-Methyl- and 4-ethyloctanoic acids were present at concentrations greatly above threshold levels in all lamb fats tested, and thus upon hydrolysis would contribute species-related flavors to lamb. 4-Methylnonanoic concentrations in lamb fats ranged from nondetectable to greater than the threshold level, and therefore this compound would not always contribute to the species-related flavors of lamb. Lean meat samples contained very low concentrations of 4-methyl- and 4-ethyloctanoic acids. 10.1016/0309-1740(92)90024-X
Novel branched-chain fatty acids in certain fish oils. Ratnayake W M,Olsson B,Ackman R G Lipids Methyl-branched fatty acids, which are usually minor components (equal or less than 0.1%) in fish oils, were concentrated in the non-urea-complexing fraction along with polyunsaturated fatty acids during the enrichment of omega-3 fatty acids from certain fish oils via the urea complexation process. The methyl-branched fatty acids in the omega-3 polyunsaturated fatty acid concentrates, which were prepared from three fish body oils, were characterized by gas chromatography and gas chromatography/mass spectrometry. Among the major branched-chain fatty acids expected and identified were the known isoprenoid acids--mainly 4,8,12-trimethyltridecanoic, pristanic, and phytanic--and the well-known iso and anteiso structures. Two novel phytol-derived multimethyl-branched fatty acids, 2,2,6,10,14-pentamethylpentadecanoic and 2,3,7,11,15-pentamethylhexadecanoic, were identified in redfish (Sebastes sp.) oil. These two fatty acids were absent in oils from menhaden (Brevoortia tyrannus) and Pacific salmon (mixed, but mostly from sockeye, Oncorhynchus nerka). The major branched-chain fatty acid in the salmon oil, 7-methyl-7-hexadecenoic acid, was also present to a moderate extent in menhaden oil. A novel vicinal dimethyl-branched fatty acid, 7,8-dimethyl-7-hexadecenoic was detected in all of the fish oils examined, but was most important in the salmon oil. Three monomethyl-branched fatty acids, 11-methyltetradecanoic acid, and 11- and 13-methylhexadecanoic, hitherto undescribed in fish lipids, were also detected in salmon, redfish and menhaden oils.
Escherichia coli coculture for de novo production of esters derived of methyl-branched alcohols and multi-methyl branched fatty acids. Microbial cell factories BACKGROUND:A broad diversity of natural and non-natural esters have now been made in bacteria, and in other microorganisms, as a result of original metabolic engineering approaches. However, the fact that the properties of these molecules, and therefore their applications, are largely defined by the structural features of the fatty acid and alcohol moieties, has driven a persistent interest in generating novel structures of these chemicals. RESULTS:In this research, we engineered Escherichia coli to synthesize de novo esters composed of multi-methyl-branched-chain fatty acids and short branched-chain alcohols (BCA), from glucose and propionate. A coculture engineering strategy was developed to avoid metabolic burden generated by the reconstitution of long heterologous biosynthetic pathways. The cocultures were composed of two independently optimized E. coli strains, one dedicated to efficiently achieve the biosynthesis and release of the BCA, and the other to synthesize the multi methyl-branched fatty acid and the corresponding multi-methyl-branched esters (MBE) as the final products. Response surface methodology, a cost-efficient multivariate statistical technique, was used to empirical model the BCA-derived MBE production landscape of the coculture and to optimize its productivity. Compared with the monoculture strategy, the utilization of the designed coculture improved the BCA-derived MBE production in 45%. Finally, the coculture was scaled up in a high-cell density fed-batch fermentation in a 2 L bioreactor by fine-tuning the inoculation ratio between the two engineered E. coli strains. CONCLUSION:Previous work revealed that esters containing multiple methyl branches in their molecule present favorable physicochemical properties which are superior to those of linear esters. Here, we have successfully engineered an E. coli strain to broaden the diversity of these molecules by incorporating methyl branches also in the alcohol moiety. The limited production of these esters by a monoculture was considerable improved by a design of a coculture system and its optimization using response surface methodology. The possibility to scale-up this process was confirmed in high-cell density fed-batch fermentations. 10.1186/s12934-022-01737-0
Long-chain syn-1-phenylalkane-1,3-diyl diacetates, related phenylalkane derivatives, and sec-alcohols, all possessing dominantly iso-branched chain termini, and 2/3-methyl-branched fatty acids from Primula veris L. (Primulaceae) wax. Radulović Niko S,Živković Stošić Milena Z Phytochemistry Herein, the results of the first study of non-flavonoid constituents of aboveground surface-wax washings of Primula veris L. (Primulaceae) are presented. Chromatography of the washings yielded a minor fraction composed of n-, iso-, and anteiso-series of long-chained syn-1-phenylalkane-1,3-diyl diacetates, 3-oxo-1-phenylalkan-1-yl acetates, 1-phenylalkane-1,3-diones, 1-hydroxy-1-phenylalkan-3-ones, sec-alcohols (2- to 10-alkanols), and n-, iso-, anteiso-, 2-methylalkanoic and 3-methylalkanoic acids; 118 of these constituents represent up to now unreported natural compounds. The structural/stereochemical elucidation was accomplished by the synthesis of authentic standards, derivatization reactions, the use of gas chromatographic retention data and detailed 1D and 2D-NMR analyses of the obtained complex chromatographic fraction. Primula veris produces unusually high amounts of branched long-chained metabolites (>60%) except for the fatty acids where the percentage of branched isomers is comparable to the ones with n-chains. Noteworthy is the fact that long-chained α- and β-methyl substituted fatty acids were detected herein for the first time in the kingdom Plantae. 10.1016/j.phytochem.2021.112732
Self-assembly of long chain fatty acids: effect of a methyl branch. Liljeblad Jonathan F D,Tyrode Eric,Thormann Esben,Dublanchet Ann-Claude,Luengo Gustavo,Magnus Johnson C,Rutland Mark W Physical chemistry chemical physics : PCCP The morphology and molecular conformation of Langmuir-Blodgett deposited and floating monolayers of a selection of straight chain (eicosanoic acid, EA), iso (19-methyl eicosanoic acid, 19-MEA), and anteiso (18-methyl eicosanoic acid, 18-MEA) fatty acids have been investigated by Vibrational Sum Frequency Spectroscopy (VSFS), AFM imaging, and the Langmuir trough. While the straight chain fatty acid forms smooth, featureless monolayers, all the branched chain fatty acids display 10-50 nm sized domains (larger for 19-MEA than the 18-MEA) with a homogeneous size distribution. A model is suggested to explain the domain formation and size in terms of the branched fatty acid packing properties and the formation of hemispherical caps at the liquid-air interface. No difference between the chiral (S) form and the racemic mixture of the 18-MEA is observed with any of the utilized techniques. The aliphatic chains of the straight chain fatty acids appear to be oriented perpendicular to the sample surface, based on an orientational analysis of VSFS data and the odd/even effect. In addition, the selection of the subphase (neat water or CdCl2 containing water buffered to pH 6.0) used for the LB-deposition has a profound influence on the monolayer morphology, packing density, compressibility, and conformational order. Finally, the orientation of the 19-MEA dimethyl moiety is estimated, and a strategy for performing an orientational analysis to determine the complete molecular orientation of the aliphatic chains of 19-MEA and 18-MEA is outlined and discussed. 10.1039/c4cp00512k
Quantification of Very-Long-Chain and Branched-Chain Fatty Acids in Plasma by Liquid Chromatography-Tandem Mass Spectrometry. Methods in molecular biology (Clifton, N.J.) Peroxisomal disorders are a heterogeneous group of genetic disorders caused by impaired peroxisomal biogenesis or by defects in single peroxisomal proteins. The most common peroxisomal disorders are Zellweger spectrum disorders (ZSDs), due to pathogenic variants in one of the 13 PEX genes, and X-linked adrenoleukodystrophy/adrenomyeloneuropathy (X-ALD/AMN), due to pathogenic variants in ATP-binding cassette transporter type D1 (ABCD1) gene. Peroxisomes perform multiple essential cellular functions, including β-oxidation of very-long-chain fatty acids (VLCFAs), pristanic acid and some bile acid intermediates, and α-oxidation of phytanic acid. In most patients, abnormal levels of VLCFAs and/or branched-chain fatty acids (BCFAs, e.g., phytanic and pristanic acids) are present; hence, measuring these analytes is critical when suspecting a peroxisomal disorder. This chapter describes a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to quantify VLCFAs and BCFAs in plasma or serum for the diagnosis of peroxisomal disorders. The method consists of an acid hydrolysis step to release the fatty acids from their coenzyme A esters followed by derivatization using oxalyl chloride, dimethylaminoethanol, and then methyl iodide. The trimethyl-amino-ethyl (TMAE) iodide ester derivatives are analyzed using UPLC-MS/MS in positive electrospray ionization and multiple reaction-monitoring (MRM) mode. Quantitation is performed using a five-point calibration curve after normalizing with deuterated internal standards. 10.1007/978-1-0716-2565-1_46
Characterization of novel methyl-branched chain fatty acids from a halophilic Bacillus species. Carballeira N M,Miranda C,Lozano C M,Nechev J T,Ivanova A,Ilieva M,Tzvetkova I,Stefanov K Journal of natural products The 4-methylated fatty acids 4,9-dimethyldecanoic, 4,11-dimethyldodecanoic, 4,10-dimethyldodecanoic, and 4,13-dimethyltetradecanoic acid as well as the 2-methylated fatty acids 2,13-dimethyltetradecanoic and 2,12-dimethyltetradecanoic acid were identified for the first time in nature in the halophilic bacterium Bacillus sp. isolated from the salt pans of Burgas in Bulgaria. The principal fatty acids in this bacterium were a series of iso-anteiso fatty acids with chain lengths between C11 and C19, but an interesting series of linear alkylbenzene fatty acids with chain lengths between C10 and C14, such as 12-phenyldodecanoic acid, were also identified. The novel 4-methylated fatty acids were characterized using a combination of GC-MS and chemical transformations such as N-acylpyrrolidide derivatization. The 2-methylated fatty acids were also identified by GC-MS and gas chromatographic coelution with synthetic samples. The novel methyl-branched fatty acids probably originated from the selective incorporation of methylmalonyl-CoA by one of the fatty acid-synthesizing enzymes of the bacterium.
Monomethyl branched-chain fatty acids enriched bacterial oil production by furan aldehydes tolerant halophile Lentibacillus salarius strain BPIITR using non-detoxified sugarcane bagasse. Bioresource technology The structural diversity of monomethyl branched-chain fatty acids (mBCFAs) expanded their application in biolubricants, biofuels for enhancing cold flow and thermo-oxidative properties. Current study focuses on mBCFAs production from sugarcane bagasse hydrolysate in biorefinery approach with halophilic Lentibacillus salarius BPIITR. Halophilic bacterium exhibited tolerance towards furan aldehydes up to 150 mM in minimal medium and produced 3.40 ± 0.13 and 2.47 ± 0.15 gL lipid rich in mBCFAs, in xylose and glucose rich non-detoxified hydrolysate, respectively at bench-scale bioreactor. In addition, 2,5-furandicarboxylic acid and 2-furancarboxylic acids were co-produced as value-added products up to 41.34 ± 4.73 and 59.84 ± 5.17 mM, respectively. The biosynthesized bacterial oil exhibited onset oxidation temperature of 319.5 °C and low temperature viscosity ratio of 2.92. The accumulated lipid was rich in triacylglycerol content more than 67 % with 12-methyl tetradecanoic acid as major fatty acid. 10.1016/j.biortech.2023.128787
Association of circulating branched chain fatty acids with insulin sensitivity and beta cell function in the PROMISE cohort. Lipids Branched chain fatty acids (BCFAs) are mainly saturated fatty acids with a methyl branch on the penultimate or antepenultimate carbon atom. While BCFAs are endogenously produced via the catabolism of branched chain amino acids, the primary exogenous source of BCFAs in the human body is via the diet, including dairy products. Recently, BCFAs have been identified as having a potentially protective role in the etiology of cardiometabolic disorders although current literature is limited. We aimed to investigate the longitudinal associations of circulating BCFAs across four serum pools with insulin sensitivity, beta cell function, and glucose concentrations in the PROMISE Cohort. Estimates of insulin sensitivity were assessed using Matsuda's insulin sensitivity index (ISI) and the homeostasis model assessment of insulin sensitivity (HOMA2). Estimates of beta cell function were determined using the insulinogenic index divided by HOMA insulin resistance and the insulin secretion-sensitivity index-2 (ISSI-2). Baseline serum samples were analyzed for BCFAs using gas-chromatography flame ionization detection. Longitudinal associations were determined using generalized estimating equations. In the free fatty acid (FFA) pool, iso15:0 and anteiso15:0 were positively associated with logHOMA2 (iso15:0 logHOMA2-%S: β = 6.86, 95% CI: [1.64, 12.36], p < 0.05, anteiso15:0 logHOMA2-%S: β = 6.36, 95% CI: [0.63, 12.42], p < 0.05) while anteiso14:0 was inversely associated with measures of insulin sensitivity (iso14:0 logHOMA2-%S: β = -2.35, 95% CI: [-4.26, -0.40], p < 0.05, logISI: β = -2.30, 95% CI: [-4.32, -0.23], p < 0.05, anteiso14:0 logHOMA2-%S: β = -4.72, 95% CI: [-7.81, -1.52], p < 0.05, logISI: β = -6.13, 95% CI: [-9.49, -2.66], p < 0.01). Associations in other pools were less consistent. We identified the potential importance of specific BCFAs, specifically iso14:0, anteiso14:0, iso15:0, anteiso15:0, in cardiometabolic phenotypes underlying type 2 diabetes. 10.1002/lipd.12373
The role of 2-hydroxyacyl-CoA lyase, a thiamin pyrophosphate-dependent enzyme, in the peroxisomal metabolism of 3-methyl-branched fatty acids and 2-hydroxy straight-chain fatty acids. Casteels M,Sniekers M,Fraccascia P,Mannaerts G P,Van Veldhoven P P Biochemical Society transactions 2-Hydroxyphytanoyl-CoA lyase (abbreviated as 2-HPCL), renamed to 2-hydroxyacyl-CoA lyase (abbreviated as HACL1), is the first peroxisomal enzyme in mammals that has been found to be dependent on TPP (thiamin pyrophosphate). It was discovered in 1999, when studying alpha-oxidation of phytanic acid. HACL1 has an important role in at least two pathways: (i) the degradation of 3-methyl-branched fatty acids like phytanic acid and (ii) the shortening of 2-hydroxy long-chain fatty acids. In both cases, HACL1 catalyses the cleavage step, which involves the splitting of a carbon-carbon bond between the first and second carbon atom in a 2-hydroxyacyl-CoA intermediate leading to the production of an (n-1) aldehyde and formyl-CoA. The latter is rapidly converted into formate and subsequently to CO(2). HACL1 is a homotetramer and has a PTS (peroxisomal targeting signal) at the C-terminal side (PTS1). No deficiency of HACL1 has been described yet in human, but thiamin deficiency might affect its activity. 10.1042/BST0350876
Viscosity of Nanoconfined Branched-Chain Fatty Acids Studied by Resonance Shear Measurements. Langmuir : the ACS journal of surfaces and colloids Lubricant performance can be improved using additives such as organic friction modifiers (OFMs) and is influenced by their conformation and properties in the space confined between the substrate surfaces, rendering the detailed property analysis of confined OFMs and lubricants a matter of high practical significance. To date, studies on fatty acids as confined OFMs have mainly focused on linear- and unsaturated-chain molecules, leaving branched-chain structures underexplored. To bridge this gap, we used resonance shear measurements in this study to probe the viscosity of two branched-chain C fatty acids (isostearic acid T and isostearic acid) confined between mica surfaces at different applied normal loads () and surface separation distances (). The viscosity parameter () of both acids significantly increased at < ∼4 nm because of structuring and was lower for isostearic acid than that for isostearic acid T at > ∼0.6 mN. This reversal of bulk viscosity order under nanoconfinement was ascribed to the ability of the bulky methyl-substituted side chain of isostearic acid to prevent ordering in the nanospace between the mica surfaces and thus preserve fluidlike properties. The obtained results provide fundamental insights into the lubricity of branched-chain fatty acids and are expected to promote the development of novel high-performance OFMs. 10.1021/acs.langmuir.2c02090
[Odd- and branched-chain fatty acids in milk fat--characteristic and health properties]. Adamska Agata,Rutkowska Jarosława Postepy higieny i medycyny doswiadczalnej (Online) This review analyzes the current state of knowledge on odd- and branched-chain fatty acids present in milk fat. Special attention is devoted to the characteristic, synthesis in ruminants, factors affecting their content in milk fat and pro-health properties of these compounds. The group of odd- and branched-chain fatty acids includes mainly saturated fatty acids with one or more methyl branches in the iso or anteiso position. These fatty acids are largely derived from ruminal bacteria and they have been transferred to ruminant tissue (milk and meat). For that reason they have been used as biomarkers of rumen fermentation. Odd- and branched-chain fatty acids are exogenous products for humans, and therefore have specific properties. The results of research from recent decades show that odd- and branched-chain fatty acids have anti-cancer activity. Branched-chain fatty acids may reduce the incidence of necrotizing enterocolitis. Additionally, these compounds have a beneficial effect on proper tissue function and on functioning and development of the infant gut, whereas odd-chain fatty acids are considered as biomarkers of milk fat intake by humans. So far, not all the mechanisms of activity of these compounds are known thoroughly. They should be more carefully studied for application of their biological effects in prevention and treatment. 10.5604/17322693.1118188
The synthesis of branched-chain fatty acids is limited by enzymatic decarboxylation of ethyl- and methylmalonyl-CoA. Dewulf Joseph P,Gerin Isabelle,Rider Mark H,Veiga-da-Cunha Maria,Van Schaftingen Emile,Bommer Guido T The Biochemical journal Most fatty acids (FAs) are straight chains and are synthesized by fatty acid synthase (FASN) using acetyl-CoA and malonyl-CoA units. Yet, FASN is known to be promiscuous as it may use methylmalonyl-CoA instead of malonyl-CoA and thereby introduce methyl-branches. We have recently found that the cytosolic enzyme ECHDC1 degrades ethylmalonyl-CoA and methylmalonyl-CoA, which presumably result from promiscuous reactions catalyzed by acetyl-CoA carboxylase on butyryl- and propionyl-CoA. Here, we tested the hypothesis that ECHDC1 is a metabolite repair enzyme that serves to prevent the formation of methyl- or ethyl-branched FAs by FASN. Using the purified enzyme, we found that FASN can incorporate not only methylmalonyl-CoA but also ethylmalonyl-CoA, producing methyl- or ethyl-branched FAs. Using a combination of gas-chromatography and liquid chromatography coupled to mass spectrometry, we observed that inactivation of ECHDC1 in adipocytes led to an increase in several methyl-branched FAs (present in different lipid classes), while its overexpression reduced them below wild-type levels. In contrast, the formation of ethyl-branched FAs was observed almost exclusively in ECHDC1 knockout cells, indicating that ECHDC1 and the low activity of FASN toward ethylmalonyl-CoA efficiently prevent their formation. We conclude that ECHDC1 performs a typical metabolite repair function by destroying methyl- and ethylmalonyl-CoA. This reduces the formation of methyl-branched FAs and prevents the formation of ethyl-branched FAs by FASN. The identification of ECHDC1 as a key modulator of the abundance of methyl-branched FAs opens the way to investigate their function. 10.1042/BCJ20190500
4-Methyl-2-oxopentanoate oxidation by rat skeletal-muscle mitochondria. Van Hinsbergh V W,Veerkamp J H,Glatz J F The Biochemical journal 1. Oxidative decarboxylation of 4-methyl-2-oxopentanoate (2-oxoisocaproate) by mitochondria of rat skeletal muscle showed biphasic kinetics. Two apparent Km values of 9.1 micronM and 0.78 mM were established. In broken mitochondria the rate of oxidation was lower and only the higher apparent Km value was found. 2. Isovalerylcarnitine inhibited 4-methyl-2-oxopentanoate oxidation in the presence and absence of carnitine, but isovaleryl-CoA had no inhibitory effect. 3. Addition of ADP enhanced 4-methyl-2-oxopentanolate oxidation. Malate, succinate and 2-oxoglutarate additionally increased the rate of oxidation, but in the absence of ADP succinate and 2-oxoglutarate inhibited. 4. Addition of rotenone and simultaneous addition of carbonyl cyanide p-trifluoromethoxyphenyl-hydrazone (FCCP) and valinomycin markedly decreased 4-methyl-2-oxopentanoate oxidation. 5. These observations indicate that the branched-chain 2-oxo acid dehydrogenase complex is situated on the inner side of the mitochondrial inner membrane. 6. In mitochondria and homogenates CO2 was only produced by oxidative decarbosylation of 4-methyl-2-oxopentanoate. In intact muscle oxidation of this oxo acid proceeds more to completeness. 7. The physiological significance of intermediate formation during oxidation of branched-chain amino acids is discussed. 10.1042/bj1820353
Isolated isobutyryl-CoA dehydrogenase deficiency: an unrecognized defect in human valine metabolism. Roe C R,Cederbaum S D,Roe D S,Mardach R,Galindo A,Sweetman L Molecular genetics and metabolism A 2-year-old female was well until 12 months of age when she was found to be anemic and had dilated cardiomyopathy. Total plasma carnitine was 6 microM and acylcarnitine analysis while receiving carnitine supplement revealed an increase in the four-carbon species. Urine organic acids were normal. In vitro analysis of the mitochondrial pathways for beta oxidation, and leucine, valine, and isoleucine metabolism was performed in fibroblasts using stable isotope-labeled precursors to these pathways followed by acylcarnitine analysis by tandem mass spectrometry. 16-2H3-palmitate was metabolized normally down to the level of butyryl-CoA thus excluding SCAD deficiency. 13C6-leucine and 13C6-isoleucine were also metabolized normally. 13C5-valine incubation revealed a significant increase in 13C4-isobutyrylcarnitine without any incorporation into propionylcarnitine as is observed normally. These same precursors were also evaluated in fibroblasts with proven ETF-QO deficiency in which acyl-CoA dehydrogenase deficiencies in each of these pathways was clearly identified. These results indicate that in the human, there is an isobutyryl-CoA dehydrogenase which exists as a separate enzyme serving only the valine pathway in addition to the 2-methyl branched-chain dehydrogenase which serves both the valine and the isoleucine pathways in both rat and human. 10.1006/mgme.1998.2758
Reanalysis of mGWAS results and in vitro validation show that lactate dehydrogenase interacts with branched-chain amino acid metabolism. European journal of human genetics : EJHG The assignment of causative genes to noncoding variants identified in genome-wide association studies (GWASs) is challenging. We show how combination of knowledge from gene and pathway databases and chromatin interaction data leads to reinterpretation of published quantitative trait loci for blood metabolites. We describe a previously unidentified link between the rs2403254 locus, which is associated with the ratio of 3-methyl-2-oxobutanoate and alpha-hydroxyisovalerate levels, and the distal LDHA gene. We confirmed that lactate dehydrogenase can catalyze the conversion between these metabolites in vitro, suggesting that it has a role in branched-chain amino acid metabolism. Examining datasets from the ENCODE project we found evidence that the locus and LDHA promoter physically interact, showing that LDHA expression is likely under control of distal regulatory elements. Importantly, this discovery demonstrates that bioinformatic workflows for data integration can have a vital role in the interpretation of GWAS results. 10.1038/ejhg.2015.106
Molecular biosignatures reveal common benthic microbial sources of organic matter in ooids and grapestones from Pigeon Cay, The Bahamas. O'Reilly S S,Mariotti G,Winter A R,Newman S A,Matys E D,McDermott F,Pruss S B,Bosak T,Summons R E,Klepac-Ceraj V Geobiology Ooids are sedimentary grains that are distributed widely in the geologic record. Their formation is still actively debated, which limits our understanding of the significance and meaning of these grains in Earth's history. Central questions include the role played by microbes in the formation of ooids and the sources of ubiquitous organic matter within ooid cortices. To address these issues, we investigated the microbial community composition and associated lipids in modern oolitic sands at Pigeon Cay on Cat Island, The Bahamas. Surface samples were taken along a transect from the shallow, turbulent surf zone to calmer, deeper water. Grains transitioned from shiny and abraded ooids in the surf zone, to biofilm-coated ooids at about 3 m water depth. Further offshore, grapestones (cemented aggregates of ooids) dominated. Benthic diatoms and Proteobacteria dominated biofilms. Taxa that may promote carbonate precipitation were abundant, particularly those associated with sulfur cycling. Compared to the lipids associated with surface biofilms, relict lipids bound within carbonate exhibited remarkably similar profiles in all grain types. The enhanced abundance of methyl-branched fatty acids and β-hydroxy fatty acids, 1-O-monoalkyl glycerol ethers and hopanoids bound within ooid and grapestone carbonate confirms a clear association of benthic sedimentary bacteria with these grains. Lipids bound within ooid cortices also contain molecular indicators of microbial heterotrophic degradation of organic matter, possibly in locally reducing conditions. These included the loss of labile unsaturated fatty acids, enhanced long-chain fatty acids/short-chain fatty acids, enriched stable carbon isotopes ratios of fatty acids, and very high stanol/stenol ratios. To what extent some of these molecular signals are derived from later heterotrophic endolithic activity remains to be fully resolved. We speculate that some ooid carbonate forms in microbial biofilms and that early diagenetic degradation of biofilms may also play a role in early stage carbonate precipitation around ooids. 10.1111/gbi.12196
Rett Syndrome: A Focus on Gut Microbiota. Borghi Elisa,Borgo Francesca,Severgnini Marco,Savini Miriam Nella,Casiraghi Maria Cristina,Vignoli Aglaia International journal of molecular sciences Rett syndrome (RTT) is an X-linked neurodevelopmental disorder affecting 1 in 10,000 live female births. Changes in microbiota composition, as observed in other neurological disorders such as autism spectrum disorders, may account for several symptoms typically associated with RTT. We studied the relationship between disease phenotypes and microbiome by analyzing diet, gut microbiota, and short-chain fatty acid (SCFA) production. We enrolled eight RTT patients and 10 age- and sex-matched healthy women, all without dietary restrictions. The microbiota was characterized by 16S rRNA gene sequencing, and SCFAs concentration was determined by gas chromatographic analysis. The RTT microbiota showed a lower α diversity, an enrichment in , spp., and spp., and a slight depletion in . Fecal SCFA concentrations were similar, but RTT samples showed slightly higher concentrations of butyrate and propionate, and significant higher levels in branched-chain fatty acids. Daily caloric intake was similar in the two groups, but macronutrient analysis showed a higher protein content in RTT diets. Microbial function prediction suggested in RTT subjects an increased number of microbial genes encoding for propionate and butyrate, and amino acid metabolism. A full understanding of these critical features could offer new, specific strategies for managing RTT-associated symptoms, such as dietary intervention or pre/probiotic supplementation. 10.3390/ijms18020344
Effect of grazing pastures with different botanical composition by lambs on rumen fatty acid metabolism and fatty acid pattern of longissimus muscle and subcutaneous fat. Lourenço M,Van Ranst G,De Smet S,Raes K,Fievez V Animal : an international journal of animal bioscience In order to study the effect of grazing pastures with a different botanical composition on rumen and intramuscular fatty acid metabolism, 21 male lambs were assigned to three botanically different pastures: botanically diverse (BD) (consisting for 65% of a variety of grass species); Leguminosa rich (L) (consisting for 61% of Leguminosae) and intensive English ryegrass (IR) (with 69% Lolium perenne). Pastures were sampled weekly for 12 weeks for analysis of their fatty acid content and composition and on nine occasions to determine the botanical composition. Ruminal and abomasal contents were sampled at slaughter and muscle and subcutaneous fat 24 h after slaughter. All samples were prepared and analysed for fatty acid composition. The L pasture showed a higher fatty acid content (29.8 mg/g dry matter (DM) v. 18.5 and 25.5 mg/g DM, for BD and IR pastures, respectively), but the sum of the proportions of the major polyunsaturated fatty acids, C18:2 n-6 and C18:3 n-3, were similar for the three pastures (69.9, 69.4 and 71.1% of fatty acids methyl esters (FAME) for BD, L and IR pastures, respectively). The BD pasture was richer in C18:2 n-6 (18.2% of FAME), while IR pasture had a higher C18:3 n-3 content (57.2% of FAME). Rumen data showed that animals grazing the BD pasture presented higher proportions of biohydrogenation intermediates, mainly C18:1 t11, C18:2 t11c15 and CLA c9t11, suggesting an inhibition of biohydrogenation. These changes were associated with shifts in the rumen microbial population as indicated by differences in the rumen pattern of volatile fatty acids, microbial odd- and branched-chain fatty acids. In L pasture animals, the content of C18:2 n-6 and C18:3 n-3 in the abomasum and subcutaneous fat was higher. Finally, higher proportions of C20:4 n-6, C20:5 n-3 and C22:5 n-3 and higher indices for elongation and desaturation activity in the intramuscular fat of BD grazing animals suggest some stimulation of elongation and desaturation of long-chain fatty acids, although this also might have been provoked partially by reduced fat deposition (due to a lower growth rate of the animals). 10.1017/S1751731107703531
Dual role of a single multienzyme complex in the oxidative decarboxylation of pyruvate and branched-chain 2-oxo acids in Bacillus subtilis. Lowe P N,Hodgson J A,Perham R N The Biochemical journal The pyruvate dehydrogenase and branched-chain 2-oxo acid dehydrogenase activities of Bacillus subtilis were found to co-purify as a single multienzyme complex. Mutants of B. subtilis with defects in the pyruvate decarboxylase (E1) and dihydrolipoamide dehydrogenase (E3) components of the pyruvate dehydrogenase complex were correspondingly affected in branched-chain 2-oxo acid dehydrogenase complex activity. Selective inhibition of the E1 or lipoate acetyltransferase (E2) components in vitro led to parallel losses in pyruvate dehydrogenase and branched-chain 2-oxo acid dehydrogenase complex activity. The pyruvate dehydrogenase and branched-chain 2-oxo acid dehydrogenase complexes of B. subtilis at the very least share many structural components, and are probably one and the same. The E3 component appeared to be identical for the pyruvate dehydrogenase, 2-oxoglutarate dehydrogenase and branched-chain 2-oxo acid dehydrogenase complexes in this organism and to be the product of a single structural gene. Long-chain branched fatty acids are thought to be essential for maintaining membrane fluidity in B. subtilis, and it was observed that the ace (pyruvate dehydrogenase complex) mutant 61142 was unable rapidly to take up acetoacetate, unlike the wild-type, indicative of a defect in membrane permeability. A single pyruvate dehydrogenase and branched-chain 2-oxo acid dehydrogenase complex can be seen as an economical means of supplying two different sets of essential metabolites. 10.1042/bj2150133
Lipoylation of acyltransferase components of alpha-ketoacid dehydrogenase complexes. Fujiwara K,Okamura-Ikeda K,Motokawa Y The Journal of biological chemistry Lipoic acid is a prosthetic group of the acyltransferase components of the pyruvate, alpha-ketoglutarate, and branched chain alpha-ketoacid dehydrogenase complexes, protein X of the eukaryotic pyruvate dehydrogenase complex, and H-protein of the glycine cleavage system. We have purified lipoyl-AMP:Nepsilon-lysine lipoyltransferase I and II from bovine liver mitochondria employing apoH-protein as an acceptor of lipoic acid (Fujiwara, K., Okamura-Ikeda, K., and Motokawa, Y. (1994) J. Biol. Chem. 269, 16605-16609). In this study, we demonstrated the lipoylation of the lipoyl domains of the mammalian pyruvate (LE2p), alpha-ketoglutarate (LE2k), and branched chain alpha-keto acid (LE2b) dehydrogenase complexes using the purified lipoyltransferase I and II. Lipoyltransferase I and II lipoylated LE2p and LE2k as efficiently as H-protein, but the lipoylation rate of LE2b was extremely low. Comparison of amino acid sequences surrounding the lipoylation site of these proteins shows that the conserved glutamic acid residue situated 3 residues to the N-terminal side of the lipoylation site is replaced by glutamine (Gln-41) in LE2b. When Gln-41 of LE2b was changed to Glu, the rate of lipoylation increased about 100-fold and became comparable to that of LE2p and LE2k. The replacement of the glutamic acid residue of LE2p (Glu-169) and LE2k (Glu-40) by glutamine resulted in decrease in the lipoylation rate more than 100-fold. These results suggest that the glutamic acid residue plays an important role in the lipoylation reaction possibly functioning as a recognition signal. Gly-27 and Gly-54 of LE2k are also well conserved among the lipoyl domains of the alpha-ketoacid dehydrogenase complexes and H-protein. The mutagenesis experiments of these residues indicated that the glycine residue situated 11 residues to the C-terminal side of the lipoylation site (Gly-54 of LE2k) is important for the folding of lipoyl domain, and that existence of a small residue such as Gly or Cys at the position is essential for the lipoylation of these proteins. 10.1074/jbc.271.22.12932
Nocardiopsis aegyptia sp. nov., isolated from marine sediment. Sabry Soraya A,Ghanem Nevine B,Abu-Ella Gehan A,Schumann Peter,Stackebrandt Erko,Kroppenstedt Reiner M International journal of systematic and evolutionary microbiology An actinomycete, strain SNG49(T), was isolated from marine sediment of Abu Qir Bay, on the western seashore of Alexandria, Egypt. The bacterium was aerobic and Gram-positive. It produced beige to light-yellow aerial mycelium, brown substrate mycelium and straight to flexuous hyphae, but no specific spore chains. 16S rDNA sequence analysis and chemotaxonomic markers were consistent with classification of strain SNG49(T) in the genus Nocardiopsis, i.e. meso-diaminopimelic acid; no diagnostic sugars; phosphatidylcholine, phosphatidylmethylethanolamine, phosphatidylinositol, phosphatidylglycerol and diphosphatidylglycerol as polar lipids; menaquinones of the MK-10 series from MK-10(H(0)) to MK-10(H(8)); and iso/anteiso-branched and 10-methyl-branched fatty acids, the principal fatty acids being anteiso-17 : 0 and tuberculostearic acid. Nocardiopsis lucentensis and Nocardiopsis alba are the phylogenetic neighbours of strain SNG49(T), respectively showing 98.8 and 98.7 % 16S rRNA gene sequence similarity; however, moderate DNA-DNA reassociation values between these two species and strain SNG49(T) (44 and 60 %, respectively) showed that strain SNG49(T) could be clearly separated from them. These data, together with distinct physiological traits, led to the conclusion that this isolate represents a novel species within the genus Nocardiopsis, for which the name Nocardiopsis aegyptia is proposed. The type strain is SNG49(T) (=DSM 44442(T)=NRRL B-24244(T)). 10.1099/ijs.0.02814-0
Structural Analysis of the Minor Cerebrosides from a Glass Sponge Aulosaccus sp. Santalova Elena A,Denisenko Vladimir A,Dmitrenok Pavel S Lipids The minor cerebrosides from a Far-Eastern glass sponge Aulosaccus sp. were analyzed as constituents of some multi-component RP-HPLC fractions. The structures of eighteen new and one known cerebrosides were elucidated on the basis of NMR spectroscopy, mass spectrometry, optical rotation data and chemical transformations. These β-D-glucopyranosyl-(1→1)-ceramides contain sphingoid bases N-acylated with straight-chain (2R)-2-hydroxy fatty acids, namely, (2S,3S,4R,11Z)-2-aminoeicos-11-ene-1,3,4-triol, acylated with 15E-22:1, 16Z-21:1, 15Z-21:1, 15Z-20:1, 15E-20:1, 19:0, 18:0 acids, (2S,3S,4R)-2-amino-13-methyltetradecane-1,3,4-triol--with 19Z-26:1, 16Z-23:1, 23:0, 22:0 acids, (2S,3S,4R)-2-amino-14-methylpentadecane-1,3,4-triol--with 16Z-23:1, 16E-23:1, 15Z-22:1, 22:0 acids, (2S,3S,4R)-2-amino-14-methylhexadecane-1,3,4-triol, linked to 16Z-23:1, 15Z-22:1 acids, (2S,3S,4R)-2-amino-9-methylhexadecane-1,3,4-triol--to 16Z-23:1 acid, and (2S,3S,4R)-2-aminohexadecane-1,3,4-triol, attached to 15Z-22:1 acid. The 13-methyl and 9-methyl-branched trihydroxy sphingoid base backbones (C15 and C17, respectively) have not been found previously in sphingolipids. The ceramide parts, containing other backbones, present new variants of N-acylation of the marine sphingoid bases with the 2-hydroxy fatty acids. The combination of the instrumental and chemical methods used in this study improved the efficiency of the structural analysis of such complex cerebroside mixtures that gave more detailed information on glycosphingolipid metabolism of the organism. 10.1007/s11745-015-4077-x
Long-Chain Alkyl Cyanides: Unprecedented Volatile Compounds Released by Pseudomonas and Micromonospora Bacteria. Montes Vidal Diogo,von Rymon-Lipinski Anna-Lena,Ravella Srinivasa,Groenhagen Ulrike,Herrmann Jennifer,Zaburannyi Nestor,Zarbin Paulo H G,Varadarajan Adithi R,Ahrens Christian H,Weisskopf Laure,Müller Rolf,Schulz Stefan Angewandte Chemie (International ed. in English) The analysis of volatiles from bacterial cultures revealed long-chain aliphatic nitriles, a new class of natural products. Such nitriles are produced by both Gram-positive Micromonospora echinospora and Gram-negative Pseudomonas veronii bacteria, although the structures differ. A variable sequence of chain elongation and dehydration in the fatty acid biosynthesis leads to either unbranched saturated or unsaturated nitriles with an ω-7 double bond, such as (Z)-11-octadecenenitrile, or methyl-branched unsaturated nitriles with the double bond located at C-3, such as (Z)-13-methyltetradec-3-enenitrile. The nitrile biosynthesis starts from fatty acids, which are converted into their amides and finally dehydrated. The structures and biosyntheses of the 19 naturally occurring compounds were elucidated by mass spectrometry, synthesis, and feeding experiments with deuterium-labeled precursors. Some of the nitriles showed antimicrobial activity, for example, against multiresistant Staphylococcus aureus strains. 10.1002/anie.201611940
Lipids of the Tail Gland, Body and Muzzle Fur of the Red Fox, Vulpes vulpes. McLean Stuart,Davies Noel W,Nichols David S Lipids The tail gland of the red fox (Vulpes vulpes) secretes lipids containing volatile terpenes used in social communication. We have analysed lipids extracted from fur of the tail gland, body (flanks) and muzzle of foxes. GC-MS showed a novel group of iso-valerate and tiglate monoesters of alkane-1,2-diols (C18:0-22:0). There was also a larger group of Type II diesters in which a second, longer chain, fatty acid (FA) was attached to the free alcohol group. LC-MS showed the full range of diol diesters, mostly C36:0-50:0, with smaller amounts of the corresponding mono-unsaturated tiglate esters. An additional group of diesters with higher MW (C49:0-62:0) containing two long-chain FA was present in the lipids of body and muzzle fur. After saponification and GC-MS, 98 fatty acids were characterized as their methyl esters. Apart from the C5 FA, most were saturated n-, iso-, anteiso- or other methyl-branched FA (C12:0-28:0) whose structures were determined by a combination of their mass spectra and Kovats retention indices. Several FA have not previously been found in nature or in vertebrates. Thirty-four alkane-1,2-diols were found as their TMS derivatives, mostly n-, iso- or anteiso-isomers of C16:0-25:0. The tail gland had the greatest amount of wax esters, from a greater variety of FA and diols, but lacked the esters with two long-chain FA. These findings show that fox skin lipids comprise mono- and di-esters of alkane-1,2-diols, and exhibit enormous complexity due to the diversity of their constituent FA, diols and the many possible isomers of their esters. 10.1007/s11745-017-4270-1
Differential diagnosis of lipoic acid synthesis defects. Tort Frederic,Ferrer-Cortes Xènia,Ribes Antonia Journal of inherited metabolic disease Lipoic acid (LA) is an essential cofactor required for the activity of five multienzymatic complexes that play a central role in the mitochondrial energy metabolism: four 2-oxoacid dehydrogenase complexes [pyruvate dehydrogenase (PDH), branched-chain ketoacid dehydrogenase (BCKDH), 2-ketoglutarate dehydrogenase (2-KGDH), and 2-oxoadipate dehydrogenase (2-OADH)] and the glycine cleavage system (GCS). LA is synthesized in a complex multistep process that requires appropriate function of the mitochondrial fatty acid synthesis (mtFASII) and the biogenesis of iron-sulphur (Fe-S) clusters. Defects in the biosynthesis of LA have been reported to be associated with multiple and severe defects of the mitochondrial energy metabolism. In recent years, disease-causing mutations in genes encoding for proteins involved in LA metabolism have been reported: NFU1, BOLA3, IBA57, LIAS, GLRX5, LIPT1, ISCA2, and LIPT2. These studies represented important progress in understanding the pathophysiology and molecular bases underlying these disorders. Here we review current knowledge regarding involvement of LA synthesis defects in human diseases with special emphasis on the diagnostic strategies for these disorders. The clinical and biochemical characteristics of patients with LA synthesis defects are discussed and a workup for the differential diagnosis proposed. 10.1007/s10545-016-9975-4
Comparison of anacardic acid biosynthetic capability between insect-resistant and-susceptible geraniums. Hesk D,Craig R,Mumma R O Journal of chemical ecology The garden geranium (Pelargonium xhortorum) has been shown to secrete anacardic acids in the form of a viscous sticky exudate from tall glandular trichomes, and this exudate provides a sticky trap defense against small pest species. The anacardic acids from genetically related pest-resistant and -susceptible plants have been characterized, and resistance has been shown to depend upon the presence ofω5 unsaturated anacardic acids. In this study, the biosynthesis of these anacardic acids was comparatively investigated by incubating [(14)C]methyl palmìtate, margarate, stearate, oleate and linoleate on floral buds of resistant and susceptible plants. In addition, the incorporation of [(14)C]valine, -isoleucine, and -leucine into anacardic acids was also studied. Nineteen anacardic acids were quantitated utilizing an improved HPLC technique. Fatty acids and, to a much lesser extent, amino acids were incorporated into anacardic acids. There are at least two pathways of biosynthesis operating: direct elongation, and β-oxidation with reincorporation of the [(14)C]acetate, the latter being more prevalent in the resistant plant. The amino acids were processed into branched chain anacardic acids, isoleucine being the precursor of the anteiso compounds, and valine the iso branched ones. The major difference between resistant and susceptible plants was the ability of resistant plants, but not the susceptible plants, to synthesizeω5 unsaturated anacardic acids. Both types of plants were capable of directly incorporating(14)C-labeled fatty acid methy esters into anacardic acids regardless of the plant's normal anacardic acid composition, thus bypassing the plant's tightly controlled regulation of the chemical structures of anacardic acids. No evidence was found forω5 desaturation of saturated anacardic acids. A revised biosynthesis scheme is presented. 10.1007/BF00994361
Dr Brian Gibberd (1931-2006): a pioneering clinician in Refsum's disease. Wierzbicki A S,Lloyd M D Biochemical Society transactions Branched-chain fatty acids are common components of the human diet (phytanic acid) or are produced endogenously (bile acids), and are also used as medicines (ibuprofen). Owing to their branched-chain structure, they are metabolized in peroxisomes. In the case of phytanic acid, the presence of a 3-methyl group prevents beta-oxidation, and instead it undergoes one round of alpha-oxidation to allow further metabolism. Defects in this process give rise to neurological diseases and cancer. Dr Brian F. Gibberd was one of the first U.K. physicians to recognize the importance of these peroxisomal metabolic pathways in clinical medicine, and pioneered their study. This obituary recognizes his many achievements in neurology and especially in the treatment of peroxisomal disorders. The following four papers from this mini-symposium entitled 'Advances in peroxisomal alpha-, beta- and omega-oxidation' describe work done in this area as part of a collaborative study in which Dr Gibberd played a key role. This work was presented as part of the Cardiovascular Bioscience focused topic at the Life Sciences 2007 conference, and this mini-symposium was dedicated to Dr Gibberd and his important contributions to this field. 10.1042/BST0350862
Bioenergetics and anaerobic respiratory chains of aceticlastic methanogens. Welte Cornelia,Deppenmeier Uwe Biochimica et biophysica acta Methane-forming archaea are strictly anaerobic microbes and are essential for global carbon fluxes since they perform the terminal step in breakdown of organic matter in the absence of oxygen. Major part of methane produced in nature derives from the methyl group of acetate. Only members of the genera Methanosarcina and Methanosaeta are able to use this substrate for methane formation and growth. Since the free energy change coupled to methanogenesis from acetate is only -36kJ/mol CH4, aceticlastic methanogens developed efficient energy-conserving systems to handle this thermodynamic limitation. The membrane bound electron transport system of aceticlastic methanogens is a complex branched respiratory chain that can accept electrons from hydrogen, reduced coenzyme F420 or reduced ferredoxin. The terminal electron acceptor of this anaerobic respiration is a mixed disulfide composed of coenzyme M and coenzyme B. Reduced ferredoxin has an important function under aceticlastic growth conditions and novel and well-established membrane complexes oxidizing ferredoxin will be discussed in depth. Membrane bound electron transport is connected to energy conservation by proton or sodium ion translocating enzymes (F420H2 dehydrogenase, Rnf complex, Ech hydrogenase, methanophenazine-reducing hydrogenase and heterodisulfide reductase). The resulting electrochemical ion gradient constitutes the driving force for adenosine triphosphate synthesis. Methanogenesis, electron transport, and the structure of key enzymes are discussed in this review leading to a concept of how aceticlastic methanogens make a living. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference. 10.1016/j.bbabio.2013.12.002
Organic acidurias: approach, results and clinical relevance. Wadman S K,Duran M,Kamerling J P Ciba Foundation symposium More than twenty-five inherited organic acidurias have been identified during the last fifteen years. This remarkable development is due mainly to the introduction of gas chromatography, and gas chromatography combined with mass spectrometry, in paediatric laboratories for metabolic disease. The chemical approach is determined mainly by physical properties of the acid, such as their extractability and volatility. Most progress has been made with extractable acids. The techniques used for derivatization are mentioned, such as trimethylsilylation, methylation and the preparation of asymmetric derivatives for the separation of optical enantiomers. Metabolite patterns may be so characteristic that the underlying enzyme defect can be deduced. Examples are the leucine degradation defects, all encountered in the authors' laboratory: branched-chain ketoaciduria; isovaleric acidaemia; 3-methylcrotonylglycinuria; 3-methylglutaconic aciduria; and 3-hydroxy-3-methylglutaric aciduria. These abnormalities are discussed. D-glyceric aciduria is shown as an example of a not yet fully understood organic aciduria. The clinical approach varies. Metabolic acidosis is an indication for organic acid analysis in urine and plasma, but in many defects there is no acidosis, or only a transient one caused by secondary metabolites, such as lactic and 3-hydroxybutyric acids. Gas chromatography is an obligatory routine investigation in screening programmes for inborn errors of metabolism, especially for the examination of acutely ill neonates and premature babies.
Aberrant oxidation of the cholesterol side chain in bile acid synthesis of sterol carrier protein-2/sterol carrier protein-x knockout mice. Kannenberg F,Ellinghaus P,Assmann G,Seedorf U The Journal of biological chemistry Peroxisomal beta-oxidation plays an important role in the metabolism of a wide range of substrates, including various fatty acids and the steroid side chain in bile acid synthesis. Two distinct thiolases have been implicated to function in peroxisomal beta-oxidation: the long known 41-kDa beta-ketothiolase identified by Hashimoto and co-workers (Hijikata, M., Ishii, N., Kagamiyama, H., Osumi, T., and Hashimoto, T. (1987) J. Biol. Chem. 262, 8151-8158) and the recently discovered 60-kDa SCPx thiolase, that consists of an N-terminal domain with beta-ketothiolase activity and a C-terminal moiety of sterol carrier protein-2 (SCP2, a lipid carrier or transfer protein). Recently, gene targeting of the SCP2/SCPx gene has shown in mice that the SCPx beta-ketothiolase is involved in peroxisomal beta-oxidation of 2-methyl-branched chain fatty acids like pristanic acid. In our present work we have investigated bile acid synthesis in the SCP2/SCPx knockout mice. Specific inhibition of beta-oxidation at the thiolytic cleavage step in bile acid synthesis is supported by our finding of pronounced accumulation in bile and serum from the knockout mice of 3alpha,7alpha, 12alpha-trihydroxy-27-nor-5beta-cholestane-24-one (which is a known bile alcohol derivative of the cholic acid synthetic intermediate 3alpha,7alpha,12alpha-trihydroxy-24-keto-cholestano yl-coenzyme A). Moreover, these mice have elevated concentrations of bile acids with shortened side chains (i.e. 23-norcholic acid and 23-norchenodeoxycholic acid), which may be produced via alpha- rather than beta-oxidation. Our results demonstrate that the SCPx thiolase is critical for beta-oxidation of the steroid side chain in conversion of cholesterol into bile acids. 10.1074/jbc.274.50.35455
Metabolomic analysis of serum short-chain fatty acid concentrations in a mouse of MPTP-induced Parkinson's disease after dietary supplementation with branched-chain amino acids. Open medicine (Warsaw, Poland) The gut microbiota and microbial metabolites influence the enteric nervous system and the central nervous system via the microbial-gut-brain axis. Increasing body of evidence suggests that disturbances in the metabolism of peripheral branched-chain amino acids (BCAAs) can contribute to the development of neurodegenerative diseases through neuroinflammatory signaling. Preliminary research has shown that longitudinal changes in serum amino acid levels in mouse models of Parkinson's disease (PD) are negatively correlated with disease progression. Therefore, the aim of the present study was to determine the changes in serum levels of short-chain fatty acids (SCFAs) in a mouse model of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD after dietary BCAA supplementation. In our research, gas chromatography-mass spectrometry was used to detect serum SCFA concentrations. The data were then analyzed with principal component analysis and orthogonal partial least squares discriminant analysis. Finally, the correlations of serum SCFA levels with gut and motor function in MPTP-induced PD mice were explored. Propionic acid, acetic acid, butyric acid, and isobutyric acid concentrations were elevated in MPTP + H-BCAA mice compared with MPTP mice. Propionic acid concentration was increased the most, while the isovaleric acid concentration was decreased. Propionic acid concentration was positively correlated with fecal weight and water content and negatively correlated with the pole-climbing duration. In conclusion, these results not only suggest that propionic acid may be a potential biomarker for PD, but also indicate the possibility that PD may be treated by altering circulating levels of SCFA. 10.1515/med-2023-0849
[Inhibition by dipropyl acetate and its structural analogs of the glycine synthase system in liver and brain mitochondria]. Martín A,Benavides J,Ugarte M Revista espanola de fisiologia The effect of the anticonvulsive di-n-propylacetate (DPA) and some structural analogous, all branched-chain organic acids, on the glycine cleavage system in rat liver and brain mitochondria has been studied. DPA and n-propyl, prop-2-enylacetic, 4,4-di-n-propylbutyric, 2-ethyl, 3-methylvaleric acids inhibit this enzymatic activity corresponding the greatest degree of inhibition to DPA (70% and 86% inhibition in liver and brain mitochondria respectively at 10 mM DPA). 2-methyl, 3-ethyl caproic acid has an inhibitory effect on glycine cleavage activity only in liver mitochondria, but showing no effect on this activity in brain mitochondria. The inhibitory effect of DPA can explain the hyperglycinemia and hyperglycinuria in DPA-treated patients. This effect may provide also an experimental approach for the study of biochemical and pathogenia mechanisms of non-ketotic hyperglycinemia.
Synthesis of high-quality water-soluble near-infrared-emitting CdTe quantum dots capped with 3-mercaptobutyric acid. Ma Kai-Guo,Bai Jin-Yi,Fang Tan,Guo Hai-Qing Journal of nanoscience and nanotechnology Highly fluorescent CdTe quantum dots (QDs) with emission in red to near-infrared (NIR) wavelength were successfully prepared by using 3-mercaptobutyric acid (3MBA) as capping agent. The maximum of quantum yield (QY) could reach up to 82% for QDs with emission peak at 686 nm and FWHM of 66 nm at optimal conditions. The QY of these QDs could maintain above 65% in the 650-750 nm region and QDs with emission over 800 nm were still strong fluorescent (28-41%). These optical properties of CdTe quantum dots are among the best results prepared by the state-of-the-art methods, suggesting their promising applications in bio-imaging. The success of 3MBA as excellent capping agent in this method was attributed to the balanced chain length and methyl side chain in comparison to a series of linear and branched mercapto acids, namely thioglycolic acid, thiolactic acid, 3-mercaptopropionic acid, 4-mercaptobutyric acid, 5-mercaptovaleric acid, 4-mercaptovaleric acid and 3-mercapto-2-methylbutyric acid. 10.1166/jnn.2014.8071
Mechanisms responsible for regulation of branched-chain amino acid catabolism. Harris Robert A,Joshi Mandar,Jeoung Nam Ho Biochemical and biophysical research communications The branched-chain amino acids (BCAAs) are essential amino acids and therefore must be continuously available for protein synthesis. However, BCAAs are toxic at high concentrations as evidenced by maple syrup urine disease (MSUD), which explains why animals have such an efficient oxidative mechanism for their disposal. Nevertheless, it is clear that leucine is special among the BCAAs. Leucine promotes global protein synthesis by signaling an increase in translation, promotes insulin release, and inhibits autophagic protein degradation. However, leucine's effects are self-limiting because leucine promotes its own disposal by an oxidative pathway, thereby terminating its positive effects on body protein accretion. A strong case can therefore be made that the proper leucine concentration in the various compartments of the body is critically important for maintaining body protein levels beyond simply the need of this essential amino acid for protein synthesis. The goal of the work of this laboratory is to establish the importance of regulation of the branched chain alpha-ketoacid dehydrogenase complex (BCKDC) to growth and maintenance of body protein. We hypothesize that proper regulation of the activity state of BCKDC by way of its kinase (BDK) and its phosphatase (BDP) is critically important for body growth, tissue repair, and maintenance of body protein. We believe that growth and protection of body protein during illness and stress will be improved by therapeutic control of BCKDC activity. We also believe that it is possible that the negative effects of some drugs (PPAR alpha ligands) and dietary supplements (medium chain fatty acids) on growth and body protein maintenance can be countered by therapeutic control of BCDKC activity. 10.1016/j.bbrc.2003.11.007
Excessive BCAA regulates fat metabolism partially through the modification of mA RNA methylation in weanling piglets. Nutrition & metabolism BACKGROUND:Fat percentage and distribution in pigs are associated with their productive efficiency and meat quality. Dietary branched-chain amino acids (BCAA) regulate fat metabolism in weanling piglets with unknown mechanism. It is reported that N6-methyl-adenosine (mA) is involved in fat metabolism in mice. The current study was designed to investigate the relationship between dietary branched-chain amino acids and fat metabolism through N6-methyl-adenosine (mA) in weanling piglets. METHODS:A total of 18 healthy crossbred weaned piglets (Duroc × Landrace × Large White, 10.45 ± 0.41 kg) were divided into 3 treatments and were fed the low BCAA dose diet (L-BCAA), the normal dose BCAA diet (N-BCAA), or the high dose BCAA (H-BCAA) diet for 3 weeks. RESULTS:Our results show that compared with the N-BCAA group, the L-BCAA group had higher concentration of serum leptin ( < 0.05), while the H-BCAA group had lower concentration of serum adiponectin ( < 0.05). Fatty acid synthesis in pigs from the H-BCAA group was lower than those from the N-BCAA group with the down-regulation of lipogenic genes (ACACA, FASN, PPAR-r, SREBP-1c in ventral and dorsal fat, SREBP-1c in liver) and up-regulation of lipolysis genes (HSL, ATGL, CPT-1A, FABP4 in ventral fat, HSL in liver) ( < 0.05). Similarly, fatty acid synthesis in pigs from the L-BCAA group was also lower than those from the N-BCAA group with the decrease of lipogenic genes (ACACA in ventral, ACACA and FASN in dorsal fat, ACACA, FASN, SREBP-1c in liver) and the increase of lipolysis genes (ATGL, CPT-1A CD36, FABP4 in ventral fat and HSL, ATGL, CPT-1A in dorsal fat, CPT-1A) ( < 0.05). Feeding H-BCAA diet significantly reduced total mA levels in ventral and dorsal fat and liver tissues ( < 0.05). The decrease of total mA is associated with down-regulation of METTL3, METTL14 and FTO in dorsal fat and METTL3 and FTO in liver ( < 0.05). Decreased mA modification of ACACA and FASN in ventral and dorsal adipose tissues was observed in pig fed with excessive BCAA. CONCLUSION:These results suggest that insufficient or excessive BCAA decreased the fat deposition by increasing lipolysis and deceasing lipogenesis in adipose and liver tissues. Dietary excessive BCAA might regulate the process of lipid metabolism partly through the mA RNA methylation. 10.1186/s12986-019-0424-x
Detection of bacterial contamination in cultures of eucaryotic cells by gas chromatography-mass spectrometry. Elmroth I,Fox A,Holst O,Larsson L Biotechnology and bioengineering The use of gas chromatography-mass spectrometry for early detection of bacterial contaminations in cultures of baker's yeast, Penicillium chrysogenum, and an animal cell line was evaluated; muramic acid and characteristic cellular fatty acids were used as analytes. By analyzing branched-chain and cyclopropane-substituted fatty acids as methyl esters, Staphylococcus epidermidis, Bacillus subtilis, Lactobacillus reuteri, Enterobacter cloacae, and Pseudomonas fluorescens were detected in a 500-fold excess (w/w) of baker's yeast; the amounts injected corresponded to 300 ng (dry mass) of the bacteria. Contamination with Bacillus was detected in cultures of Penicillium chrysogenum and animal cells by analyzing muramic acid, both as its alditol acetate derivative, using electron impact ionization, and its trifluoroacetyl methyl glycoside derivative, using negative ion-chemical ionization. The trifluoroacetylated derivative was detected in injected amounts corresponding to 1 x 10(3) bacterial cells in the contaminated animal cell line, whereas amounts corresponding to 1 x 10(5) bacteria were required for detection of the alditol acetate derivative; the amounts in the original samples were 5 x 10(5) and 5 x 10(6), respectively. However, the alditol acetate method exhibited lower chemical interferences than the trifluoroacetyl methyl glycoside procedure. The results show the potential of using gas chromatographic-mass spectrometric analysis of cellular constituents for the detection of bacterial contaminations in eucaryotic cultures as an alternative to conventional microbiological methods. 10.1002/bit.260420404
Dual Effects of Beta-Hydroxy-Beta-Methylbutyrate (HMB) on Amino Acid, Energy, and Protein Metabolism in the Liver and Muscles of Rats with Streptozotocin-Induced Type 1 Diabetes. Holeček Milan,Vodeničarovová Melita,Fingrová Radana Biomolecules Beta-hydroxy-beta-methyl butyrate (HMB) is a unique product of leucine catabolism with positive effects on protein balance. We have examined the effects of HMB (200 mg/kg/day via osmotic pump for 7 days) on rats with diabetes induced by streptozotocin (STZ, 100 mg/kg intraperitoneally). STZ induced severe diabetes associated with muscle wasting, decreased ATP in the liver, and increased α-ketoglutarate in muscles. In plasma, liver, and muscles increased branched-chain amino acids (BCAAs; valine, isoleucine, and leucine) and decreased serine. The decreases in mass and protein content of muscles and increases in BCAA concentration were more pronounced in extensor digitorum longus (fast-twitch muscle) than in soleus muscle (slow-twitch muscle). HMB infusion to STZ-treated animals increased glycemia and serine in the liver, decreased BCAAs in plasma and muscles, and decreased ATP in the liver and muscles. The effects of HMB on the weight and protein content of tissues were nonsignificant. We concluded that fast-twitch muscles are more sensitive to STZ than slow-twitch muscles and that HMB administration to STZ-treated rats has dual effects. Adjustments of BCAA concentrations in plasma and muscles and serine in the liver can be considered beneficial, whereas the increased glycemia and decreased ATP concentrations in the liver and muscles are detrimental. 10.3390/biom10111475
Temperature Driven Membrane Lipid Adaptation in Glacial Psychrophilic Bacteria. Frontiers in microbiology Bacteria inhabiting non-polar glaciers are exposed to large variations in temperature, which significantly affects the fluidity of bacterial cell membranes. In order to maintain normal functions of the cell membranes, psychrophilic bacteria adapt by changing the composition of cell membrane fatty acids. However, information on the exact pattern of cell membrane adaptability in non-polar low-temperature habitats is scarce. In the present study, 42 bacterial strains were isolated from the Ghulmet, Ghulkin, and Hopar glaciers of the Hunza Valley in the Karakoram Mountain Range, Pakistan and their cell membrane fatty acid distributions studied, using gas chromatography/mass spectrometry (GC-MS) for the analysis of fatty acid methyl esters (FAMEs) liberated by acid-catalyzed methanolysis. Furthermore, Gram-negative and Gram-positive groups were grown under different temperature settings (5, 15, 25, and 35°C) in order to determine the effect of temperature on cell membrane (CM) fatty acid distribution. The analyses identified the major groups of cell membrane fatty acids (FA) as straight-chain monounsaturated fatty acids (-MUFAs) and branched fatty acids (-FAs), accounting for more than 70% of the fatty acids analyzed. The distribution of br-FAs and -FAs in bacterial cell membranes was significantly affected by temperature, with the level of br-FAs decreasing relative to -FAs with increasing temperature. Notably, the production of polyunsaturated fatty acids (PUFAs) was only seen at lower temperatures. This study contributes to understanding, for the first time, the role of br-FAs in the maintenance of cell membrane fluidity of bacteria inhabiting non-polar habitats. 10.3389/fmicb.2020.00824
Folding kinetics of the lipoic acid-bearing domain of human mitochondrial branched chain alpha-ketoacid dehydrogenase complex. Naik Mandar T,Chang Yu-Chu,Huang Tai-huang FEBS letters A reversible two-step (native state<-->denatured state) folding mechanism based on equilibrium and stopped flow experiments is proposed for urea denaturation of the lipoyl-bearing domain (hbLBD) of human mitochondrial branched chain alpha-ketoacid dehydrogenase (BCKD) complex. The results from this circular dichroism (CD) and fluorescence study have ruled out populated kinetic or equilibrium intermediates on folding pathway of this beta-barrel domain under experimental conditions. Both studies suggested mono-exponential kinetics without any burst phases. Moreover the thermodynamic parameters DeltaG(H(2)O) and m obtained from the kinetic analysis are consistent with the equilibrium measurements. 10.1016/s0014-5793(02)03444-0
Regulation of the branched-chain 2-oxo acid dehydrogenase complex in hepatocytes isolated from rats fed on a low-protein diet. Harris R A,Paxton R,Goodwin G W,Powell S M The Biochemical journal Hepatocytes isolated from rats fed on a chow diet or a low-protein (8%) diet were used to study the effects of various factors on flux through the branched-chain 2-oxo acid dehydrogenase complex. The activity of this complex was also determined in cell-free extracts of the hepatocytes. Hepatocytes isolated from chow-fed rats had greater flux rates (decarboxylation rates of 3-methyl-2-oxobutanoate and 4-methyl-2-oxopentanoate) than did hepatocytes isolated from rats fed on the low-protein diet. Oxidizable substrates tended to inhibit flux through the branched-chain 2-oxo acid dehydrogenase, but inhibition was greater with hepatocytes isolated from rats fed on the low-protein diet. 2-Chloro-4-methylpentanoate (inhibitor of branched-chain 2-oxo acid dehydrogenase kinase), dichloroacetate (inhibitor of both pyruvate dehydrogenase kinase and branched-chain 2-oxo acid dehydrogenase kinase) and dibutyryl cyclic AMP (inhibitor of glycolysis) were effective stimulators of branched-chain oxo acid decarboxylation with hepatocytes from rats fed on a low-protein diet, but had little effect with hepatocytes from rats fed on chow diet. Activity measurements indicated that the branched-chain 2-oxo acid dehydrogenase complex was mainly (96%) in the active (dephosphorylated) state in hepatocytes from chow-fed rats, but only partially (50%) in the active state in hepatocytes from rats fed on a low-protein diet. Oxidizable substrates markedly decreased the activity state of the enzyme in hepatocytes from rats fed on a low-protein diet, but had much less effect in hepatocytes from chow-fed rats. 2-Chloro-4-methylpentanoate and dichloroacetate increased the activity state of the enzyme in hepatocytes from rats fed on a low-protein diet, but had no effect on the activity state of the enzyme in hepatocytes from chow-fed rats. The results indicate that protein starvation greatly increases the sensitivity of the hepatic branched-chain 2-oxo acid dehydrogenase complex to regulation by covalent modification. 10.1042/bj2340285
A second branched-chain alpha-keto acid dehydrogenase gene cluster (bkdFGH) from Streptomyces avermitilis: its relationship to avermectin biosynthesis and the construction of a bkdF mutant suitable for the production of novel antiparasitic avermectins. Denoya C D,Fedechko R W,Hafner E W,McArthur H A,Morgenstern M R,Skinner D D,Stutzman-Engwall K,Wax R G,Wernau W C Journal of bacteriology A second cluster of genes encoding the E1 alpha, E1 beta, and E2 subunits of branched-chain alpha-keto acid dehydrogenase (BCDH), bkdFGH, has been cloned and characterized from Streptomyces avermitilis, the soil microorganism which produces anthelmintic avermectins. Open reading frame 1 (ORF1) (bkdF, encoding E1 alpha), would encode a polypeptide of 44,394 Da (406 amino acids). The putative start codon of the incompletely sequenced ORF2 (bkdG, encoding E1 beta) is located 83 bp downstream from the end of ORF1. The deduced amino acid sequence of bkdF resembled the corresponding E1 alpha subunit of several prokaryotic and eukaryotic BCDH complexes. An S. avermitilis bkd mutant constructed by deletion of a genomic region comprising the 5' end of bkdF is also described. The mutant exhibited a typical Bkd- phenotype: it lacked E1 BCDH activity and had lost the ability to grow on solid minimal medium containing isoleucine, leucine, and valine as sole carbon sources. Since BCDH provides an alpha-branched-chain fatty acid starter unit, either S(+)-alpha-methylbutyryl coenzyme A or isobutyryl coenzyme A, which is essential to initiate the synthesis of the avermectin polyketide backbone in S. avermitilis, the disrupted mutant cannot make the natural avermectins in a medium lacking both S(+)-alpha-methylbutyrate and isobutyrate. Supplementation with either one of these compounds restores production of the corresponding natural avermectins, while supplementation of the medium with alternative fatty acids results in the formation of novel avermectins. These results verify that the BCDH-catalyzed reaction of branched-chain amino acid catabolism constitutes a crucial step to provide fatty acid precursors for antibiotic biosynthesis in S. avermitilis. 10.1128/jb.177.12.3504-3511.1995
Propionyl-CoA condensing enzyme from Ascaris muscle mitochondria. I. Isolation and characterization of multiple forms. Suarez de Mata Z,Lizardo R,Diaz F,Saz H J Archives of biochemistry and biophysics The condensation of two propionyl-CoA units or a propionyl-CoA with acetyl-CoA is required for the synthesis of 2-methylvalerate or 2-methylbutyrate, respectively, two of the major fermentation products of Ascaris anaerobic muscle metabolism. An enzyme that preferentially catalyzes the condensation of propionyl-CoA rather than acetyl-CoA has been purified from the mitochondria of the parasitic intestinal nematode Ascaris lumbricoides var. suum. The purified enzyme is over 10 times more active with propionyl-CoA than with acetyl-CoA as substrate. It also catalyzes the coenzyme A-dependent hydrolysis of acetoacetyl-CoA at a rate four times higher than the propionyl-CoA condensation reaction. The purified Ascaris condensing enzyme preferentially forms the 2-methyl-branched-chain keto acids rather than the corresponding straight chain compounds. The native molecular weight of the purified enzyme was estimated to be 160,000 by gel filtration chromatography and 158,000 by high pressure liquid chromatography. The enzyme migrated as a single protein band with Mr 40,000 during sodium dodecyl sulfate-polyacrylamide electrophoresis, indicating that the enzyme is composed of four subunits of the same molecular weight. Chromatography on CM-sephadex resulted in the isolation of two separate peaks of activity, designated as A and B. Both A and B had the same molecular weight and subunit composition. However, they differed in their specific activities and isoelectric points. The pIs of condensing enzymes A and B were 7.6 and 8.4, respectively. Propionyl-CoA was the best substrate for the condensation reaction with both enzymes. However, the specific activity of enzyme B for both propionyl-CoA condensation (3.4 mumol/min/mg protein) and acetoacetyl-CoA thiolysis (13.8 mumol/min/mg protein) was 2.4 times higher than that obtained with enzyme A. Similarly, chromatography on phosphocellulose resolved the Ascaris condensing enzyme activity into one minor and two major peaks. All of these components had the same molecular weight and subunit composition, but differed in their specific activities. The two major phosphocellulose peaks cross-reacted immunologically when examined by the Ouchterlony double immunodiffusion technique. In addition, antiserum against the phosphocellulose most active form cross-reacted with forms A and B isolated by chromatography of the enzyme on CM-Sephadex, indicating that all forms were immunochemically related. 10.1016/0003-9861(91)90344-i
Regulation of branched-chain amino acid metabolism. Harris R A,Paxton R,Goodwin G W,Kuntz M J,Shimomura Y,Han A Biochemical Society transactions 10.1042/bst0141005
Metabolic annotation of 2-ethylhydracrylic acid. Ryan Robert O Clinica chimica acta; international journal of clinical chemistry Increased levels of the organic acid, 2-ethylhydracrylic acid (2-EHA) occur in urine of subjects with impaired L(+)-isoleucine metabolism. Chiral intermediates formed during isoleucine degradation are (S) enantiomers. Blockage of (S) pathway flux drives racemization of (2S, 3S) L(+)-isoleucine and its (2S, 3R) stereoisomer, L(+)-alloisoleucine. This non-protein amino acid is metabolized to (R)-2-methylbutyryl CoA via enzymes common to branched chain amino acid degradation. Subsequently, (R) intermediates serve as alternate substrates for three valine metabolic enzymes, generating 2-EHA. Once formed, 2-EHA accumulates because it is poorly recognized by distal valine pathway enzymes. Thus, urinary 2-EHA represents a biomarker of isoleucine pathway defects. 2-EHA levels are also increased in rats exposed to the industrial solvent, ethylene glycol monomethyl ether or the neurotoxin precursor, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. In these cases, a block in (S) pathway isoleucine catabolism occurs at the level of (S)-2-methylbutyryl CoA conversion to tiglyl CoA via inhibition of electron transferring flavoprotein/ubiquinone oxidoreductase dependent reactions. Elevated urinary 2-EHA in propionyl CoA carboxylase deficiency and methylmalonic aciduria results from a buildup of distal intermediates in the (S) pathway of isoleucine degradation. In Barth syndrome and dilated cardiomyopathy with ataxia syndrome, 2-EHA is a byproduct of impeded propionyl CoA entry into the Krebs cycle. 10.1016/j.cca.2015.06.012
Effects of diabetes on the activity and content of the branched-chain alpha-ketoacid dehydrogenase complex in liver. Gibson R,Zhao Y,Jaskiewicz J,Fineberg S E,Harris R A Archives of biochemistry and biophysics Severe ketotic diabetes induced in rats by streptozotocin resulted in a reduction in activity of the hepatic branched-chain alpha-ketoacid dehydrogenase complex, regardless of whether activity was expressed on the basis of liver wet weight, total liver, liver protein, or liver DNA. A decrease in enzyme specific activity (units of enzyme activity per mg of enzyme protein) was found responsible for the reduction in measurable enzyme activity of the complex. Insulin treatment reversed the decrease in enzyme specific activity. Treatment of tissue extracts with phosphoprotein phosphatase had no effect, indicating that activity of the complex was decreased by some mechanism other than reversible phosphorylation. Specific protein components of the complex were also not found reduced by the diabetic state. Induction of severe ketotic diabetes in rats previously fed a low-protein diet resulted in activation of the enzyme as a consequence of dephosphorylation. Nevertheless, the specific activity of the dephosphorylated enzyme of diabetic, low-protein-fed rats was decreased relative to that of control, low-protein-fed animals. Reconstitution studies with tissue extracts fortified with the purified E1 component indicate that severe diabetes induces a defect in this component of the hepatic branched-chain alpha-ketoacid dehydrogenase complex. 10.1006/abbi.1993.1475
Role of activation of myocardial branched-chain 2-oxo acid dehydrogenase complex in the regulation of leucine decarboxylation during cardiac work in vitro. Hildebrandt E,Olson M S The Biochemical journal The oxidative decarboxylation of L-[1-14C]leucine was measured in the isolated perfused rat heart under both working and non-working conditions. Stimulation of decarboxylation of the labelled substrate was observed in working hearts as cardiac work was increased, and in Langendorff hearts upon increasing the coronary flow rate. The rate of L-[1-14C]leucine decarboxylation was significantly higher (P less than 0.05) in hearts working against moderate afterload pressure when compared to Langendorff hearts perfused at a matching coronary flow rate. The rate of release of 4-methyl-2-oxo[1-14C]pentanoate to the perfusate was high in Langendorff hearts, and was unaffected by changes in coronary flow. In contrast, perfusate levels of 14C-labelled 4-methyl-2-oxopentanoate decreased significantly upon the establishment of the working condition (P less than 0.05). These findings suggested an enhancement in the efficiency of the decarboxylation of the 2-oxo acid in response to cardiac work. The amount of branched-chain 2-oxo acid dehydrogenase complex present in the active form was measured in freeze-clamped hearts. Cardiac work resulted in a rapid activation of the complex (P less than 0.02) within 5 min of work when compared to control Langendorff hearts perfused at matching coronary flow rates. To a lesser extent, increasing the coronary flow rate in Langendorff-perfused hearts also led to activation of the enzyme complex. These studies suggest the following: a) L-leucine oxidation in myocardial tissue can be accelerated by exercise as it is in other tissues; b) this regulatory response can be evoked by the contractile activity of the heart itself, independent of contributions by circulating factors or nervous stimuli; and c) regulation of the activity state of the branched-chain 2-oxo acid dehydrogenase complex is involved in the mechanism by which metabolic flux through this pathway is controlled during cardiac work. 10.1042/bj2480423
A Novel Effect of Lipids Extracted from Vernix Caseosa on Regulation of Filaggrin Expression in Human Epidermal Keratinocytes. Annals of dermatology BACKGROUND:Vernix caseosa (VC), which is known as a unique human substance, is a biofilm that covers the skin of most human newborns. VC has many biological functions including anti-infective, skin cleansing and skin barrier repair. OBJECTIVE:In the study, we purpose to investigate the novel effect of lipids extracted from VC on the regulation of filaggrin (FLG) expression and anti-inflammation in normal human epidermal keratinocyte (NHEK) cells. METHODS:The lipids were extracted by chloroform/methanol (Folch method) and the major properties of fatty acid methyl esters were determined with gas chromatography-mass spectrometer. The relative viability of NHEK cells was evaluated by Cell Counting Kit 8 assay. The related expression of skin barrier protein was accessed with real-time quantitative polymerase chain reaction, Western blot and Immunofluorescence in NHEK cells with or without poly (I:C). Meanwhile, the changes of thymic stromal lymphopoietin (TSLP) and tumor necrosis factor alpha (TNF-α) are analyzed by enzyme-linked immunosorbent assay. RESULTS:VC lipids mostly contained saturated and branched chains fatty acids. The expression of mRNA and protein of FLG were significantly increased after the supplement with lipid in NHEK cells. Meanwhile, lipids reversed the inhibition of poly (I:C) on FLG. Moreover, lipids suppressed the over secretion of TSLP and TNF-α induced by poly (I:C). CONCLUSION:These results indicate that lipids extracted from VC has positive effects on the expression of FLG and anti-inflammation, suggesting that lipids of VC may be used for a reference for novel therapeutic method in reducing and remedying skin disease like atopic disease. 10.5021/ad.2019.31.6.611
Studies on the production of branched-chain alcohols in engineered Ralstonia eutropha. Lu Jingnan,Brigham Christopher J,Gai Claudia S,Sinskey Anthony J Applied microbiology and biotechnology Wild-type Ralstonia eutropha H16 produces polyhydroxybutyrate (PHB) as an intracellular carbon storage material during nutrient stress in the presence of excess carbon. In this study, the excess carbon was redirected in engineered strains from PHB storage to the production of isobutanol and 3-methyl-1-butanol (branched-chain higher alcohols). These branched-chain higher alcohols can directly substitute for fossil-based fuels and be employed within the current infrastructure. Various mutant strains of R. eutropha with isobutyraldehyde dehydrogenase activity, in combination with the overexpression of plasmid-borne, native branched-chain amino acid biosynthesis pathway genes and the overexpression of heterologous ketoisovalerate decarboxylase gene, were employed for the biosynthesis of isobutanol and 3-methyl-1-butanol. Production of these branched-chain alcohols was initiated during nitrogen or phosphorus limitation in the engineered R. eutropha. One mutant strain not only produced over 180 mg/L branched-chain alcohols in flask culture, but also was significantly more tolerant of isobutanol toxicity than wild-type R. eutropha. After the elimination of genes encoding three potential carbon sinks (ilvE, bkdAB, and aceE), the production titer improved to 270 mg/L isobutanol and 40 mg/L 3-methyl-1-butanol. Semicontinuous flask cultivation was utilized to minimize the toxicity caused by isobutanol while supplying cells with sufficient nutrients. Under this semicontinuous flask cultivation, the R. eutropha mutant grew and produced more than 14 g/L branched-chain alcohols over the duration of 50 days. These results demonstrate that R. eutropha carbon flux can be redirected from PHB to branched-chain alcohols and that engineered R. eutropha can be cultivated over prolonged periods of time for product biosynthesis. 10.1007/s00253-012-4320-9
The glycosylceramides of the nematode Caenorhabditis elegans contain an unusual, branched-chain sphingoid base. Chitwood D J,Lusby W R,Thompson M J,Kochansky J P,Howarth O W Lipids Caenorhabditis elegans was cultured in semi-defined medium containing yeast extract, soy peptone, glucose, hemoglobin, Tween 80, and sitosterol. Monoglycosylceramides were chromatographically purified from nematode extracts. Their structures were elucidated with mass spectrometry, nuclear magnetic resonance spectroscopy, and analysis of methanolysis products of the parent cerebrosides. The glycosylceramides were unusual in that the only long-chain sphingoid base detected was an iso-branched compound with a C-4 double bond (i.e., 15-methyl-2-aminohexadec-4-en-1,3-diol). Glucose was the only sugar moiety detected. The fatty acids consisted of a series of primarily straight-chain, saturated, 2-hydroxylated C20-C26 acids; some iso-branched analogs also occurred. The sphingomyelins of C. elegans were also hydrolyzed, and the same iso-branched C17 compound was the only sphingoid base detected. This is the first structural analysis of a nematode glycosphingolipid and the first report of an organism in which the long-chain sphingoid bases are entirely iso-branched.
Structural elucidation of a novel phosphonoglycosphingolipid in eggs of the sea hare Aplysia juliana. Yamaguchi Y,Ohta M,Hayashi A Biochimica et biophysica acta A novel phosphonoglycosphingolipid (AJPnGL) was isolated from eggs of the sea hare Aplysia juliana. The structure was determined to be Gal alpha 1-->2Gal beta 1-->4(2-aminoethylphosphonyl-->6)Glc beta 1-->1Cer by FAB/MS, 1H-NMR, hydrogen fluoride degradation, methylation analysis, partial acid hydrolysis and GC analysis of the component sugars, fatty acids and long-chain bases. The ceramide moiety of this lipid consisted of branched nonadeca-4-sphingenine and octadeca-4-sphingenine as main long-chain bases and palmitic acid and stearic acid as major fatty acids. Since the sugar chain (Gal alpha 1-->2Gal beta 1-->4Glc beta 1-->) and the ceramide moiety of AJPnGL were identical with those of the main neutral glycosphingolipid of eggs of A. juliana, the biosynthesis of AJPnGL may occur by the addition of 2-aminoethylphosphonate to the main neutral glycosphingolipid, Gal alpha 1-->2Gal beta 1-->4Glc beta 1-->1Cer.
The bkdR gene of Streptomyces coelicolor is required for morphogenesis and antibiotic production and encodes a transcriptional regulator of a branched-chain amino acid dehydrogenase complex. Journal of bacteriology Products from the degradation of the branched-chain amino acids valine, leucine, and isoleucine contribute to the production of a number of important cellular metabolites, including branched-chain fatty acids, ATP and other energy production, cell-cell signaling for morphological development, and the synthesis of precursors for polyketide antibiotics. The first nonreversible reactions in the degradation of all three amino acids are catalyzed by the same branched-chain alpha-keto acid dehydrogenase (BCDH) complex. Actinomycetes are apparently unique among bacteria in that they contain two separate gene clusters, each of which encodes a BCDH enzyme complex. Here, we show that one of these clusters in Streptomyces coelicolor is regulated, at least in part, at the level of transcription by the product of the bkdR gene. The predicted product of this gene is a protein with similarity to a family of proteins that respond to leucine and serve to activate transcription of amino acid utilization operons. Unlike most other members of this class, however, the S. coelicolor bkdR gene product serves to repress transcription, suggesting that the branched-chain amino acids act as inducers rather than coactivators of transcription. BkdR likely responds to the presence of branched-chain amino acids. Its role in transcriptional regulation may be rationalized by the fact that transition from vegetative growth to aerial mycelium production, the first stage of morphological development in these complex bacteria, is coincident with extensive cellular lysis generating abundant amounts of protein that likely serve as the predominant source of carbon and nitrogen for metabolism. We suggest that bkdR plays a key role in the ability of Streptomyces species to sense nutrient availability and redirect metabolism for the utilization of branched-chain amino acids for energy, carbon, and perhaps even morphogen synthesis. A null mutant of bkdR is itself defective in morphogenesis and antibiotic production, suggesting that the role of the bkdR gene product may be more global than specific nutrient utilization. 10.1128/JB.187.2.664-671.2005
Regulation of branched-chain amino acid oxidation in isolated muscles, nerves and aortas of rats. Buse M G,Jursinic S,Reid S S The Biochemical journal 1. The oxidation of the three branched-chain amino acids was regulated in parallel fashion in rat tissues studied in vitro. 2. With 0.1 mM-[1-14C]isoleucine as substrate in the presence of 5.5 mM-glucose, 14CO2 production was 0.6 mumol/2 h per g in the aorta, 0.3 in peripheral nerve, 0.2 in muscle and 0.13 in spinal cord. 3. The ratio 14C oxidized/14C incorporated into proteins with 0.1 mM-[1-14C]leucine was 1.3 in hemidiaphragms, 3.3 in sciatic nerve and 1.0 in nerves undergoing Wallerian degeneration. Leucine oxidation decreased only slightly during degeneration, but protein synthesis doubled. 4. Hemidiaphragms incubated with [1-14C]leucine or 4-methyl-2-oxo[1-14C]pentanoate increased 14CO2 production 7-9-fold as substrate concentration was increased from 0.1 to 0.5 mM; under the same conditions 14CO2 production by nerves increased only 2-3-fold. 5. 2-Oxoglutarate stimulated the oxidation of the branched-chain amino acids by muscles and peripheral nerves and the oxidation of 4-methyl-2-oxopentanoate by hemidiaphragms but not by nerves. 6. Octanoate (0.1-1.0 mM) markedly stimulated the oxidation of branched-chain amino acids and of 4-methyl-2-oxopentanoate in hemidiaphragms, but inhibited oxidation of both by peripheral nerves and spinal cord. In aortas, oxidation of isoleucine (the only substance tested) was inhibited by octanoate. 7. The effects of octanoate and 2-oxoglutarate on leucine oxidation by hemidiaphragms were additive at low concentrations. When maximally stimulating concentrations of either agent were used, addition of the other was ineffective. 8. Pyruvate inhibited the oxidation of branched-chain amino acids and 4-methyl-2-oxopentanoate in all tissues tested. 9. Insulin did not affect the oxidation of 4-methyl-2-oxopentanoate by muscles or nerves. 10. The oxidative decarboxylation of the branched-chain alpha-oxo acids is suggested as a regulatory site of branched-chain amino acid oxidation. Differences in regulation between muscle on the one hand, and nerve and aorta on the other, are discussed. 10.1042/bj1480363
Statin treatment reduces leucine turnover, but does not affect endogenous production of beta-hydroxy-beta-methylbutyrate (HMB). Metabolism: clinical and experimental BACKGROUND:Statins, or hydroxy-methyl-glutaryl coenzyme A (HMG-CoA) reductase inhibitors, are one of the most commonly prescribed medications for lowering cholesterol. Myopathic side-effects ranging from pain and soreness to critical rhabdomyolysis are commonly reported and often lead to discontinuation. The pathophysiological mechanism is, in general, ascribed to a downstream reduction of Coenzyme Q10 synthesis. HMG-CoA is a metabolite of leucine and its corresponding keto acid α-ketoisocaproic acid (KIC) and β-hydroxy-β-methylbutyrate (HMB), however, little is known about the changes in the metabolism of leucine and its metabolites in response to statins. OBJECTIVE:We aimed to investigate if statin treatment has implications on the upstream metabolism of leucine to KIC and HMB, as well as on other branched chain amino acids (BCAA). DESIGN:12 hyperlipidemic older adults under statin treatment were recruited. The study was conducted as a paired prospective study. Included participants discontinued their statin treatment for 4 weeks before they returned for baseline measurements (before). Statin treatment was then reintroduced, and the participants returned for a second study day 7 days after reintroduction (after statin). On study days, participants were injected with stable isotope pulses for measurement of the whole-body production (WBP) of all BCAA (leucine, isoleucine and valine), along with their respective keto acids and HMB. RESULTS:We found a reduced leucine WBP (22 %, p = 0.0033), along with a reduction in valine WBP (13 %, p = 0.0224). All other WBP of BCAA and keto acids were unchanged. There were no changes in the WBP of HMB. CONCLUSIONS:Our study shows that statin inhibition of HMG-CoA reductase has an upstream impact on the turnover of leucine and valine. Whether this impairment in WBP of leucine may contribute to the known pathophysiological side effects of statins on muscle remains to be further investigated. 10.1016/j.metabol.2024.155920
Formation of Key Aroma Compounds During 30 Weeks of Ripening in Gouda-Type Cheese Produced from Pasteurized and Raw Milk. Journal of agricultural and food chemistry Gouda-type cheeses were produced on a pilot-scale from raw milk (RM-G) and pasteurized milk (PM-G). Sixteen key aroma compounds previously characterized by the sensomics approach were quantitated in the unripened cheeses and at five different ripening stages (4, 7, 11, 19, and 30 weeks) by means of stable isotope dilution assays. Different trends were observed in the formation of the key aroma compounds. Short-chain free fatty acids and ethyl butanoate as well as ethyl hexanoate continuously increased during ripening but to a greater extent in RM-G. Branched-chain fatty acids such as 3-methylbutanoic acid were also continuously formed and reached a 60-fold concentration after 30 weeks, in particular in PM-G. 3-Methylbutanal and butane-2,3-dione reached a maximum concentration after 7 weeks and decreased with longer ripening. Lactones were high in the unripened cheeses and increased only slightly during ripening. Recent results have shown that free amino acids were released during ripening. The aroma compounds 3-methylbutanal, 3-methyl-1-butanol, and 3-methylbutanoic acid are suggested to be formed by microbial enzymes degrading the amino acid l-leucine following the Ehrlich pathway. To gain insight into the quantitative formation of each of the three aroma compounds, the conversion of the labeled precursors (C)-l-leucine and (H)-2-keto-4-methylpentanoic acid into the isotopically labeled aroma compounds was studied. By applying the CAMOLA approach (defined mixture of labeled and unlabeled precursor), l-leucine was confirmed as the only precursor of the three aroma compounds in the cheese with the preferential formation of 3-methylbutanoic acid. 10.1021/acs.jafc.4c01814
An insight into the role of branched-chain α-keto acid dehydrogenase (BKD) complex in branched-chain fatty acid biosynthesis and virulence of . Journal of bacteriology is a foodborne bacterial pathogen that causes listeriosis. Positive regulatory factor A (PrfA) is a pleiotropic master activator of virulence genes of that becomes active upon the entry of the bacterium into the cytosol of infected cells. can survive and multiply at low temperatures; this is accomplished through the maintenance of appropriate membrane fluidity via branched-chain fatty acid (BCFA) synthesis. Branched-chain α-keto acid dehydrogenase (BKD), which is composed of four polypeptides encoded by , , , and , is known to play a vital role in BCFA biosynthesis. Here, we constructed BKD-deficient strains by in-frame deletion of , , , and genes. To determine the role in and , mouse model challenges, plaque assay in murine L2 fibroblast, and intracellular replication in J744A.1 macrophage were conducted. BKD-deficient strains exhibited defects in BCFA composition, virulence, and PrfA-regulon function within the host cells. Transcriptomics analysis revealed that the transcript level of the PrfA-regulon was lower in Δ strain than those in the wild-type. This study demonstrates that strains lacking BKD complex components were defective in PrfA-regulon function, and full activation of wild-type may not occur within host cells in the absence of BKD. Further study will investigate the consequences of BKD deletion on PrfA function through altering BCFA catabolism.IMPORTANCE is the causative agent of listeriosis, a disease with a high mortality rate. In this study, we have shown that the deletion of BKD can impact the function of PrfA and the PrfA-regulon. The production of virulence proteins within host cells is necessary for to promote its intracellular survival and is likely dependent on membrane integrity. We thus report a link between membrane integrity and the function of PrfA. This knowledge will increase our understanding of pathogenesis, which may provide insight into the development of antimicrobial agents. 10.1128/jb.00033-24
Structure modeling-based characterization of ChnD, the 6-hydroxyhexanoate dehydrogenase from Acinetobacter sp. strain NCIMB 9871. Journal of biotechnology α,ω-Dicarboxylic acids, ω-aminoalkanoic acids, and α,ω-diaminoalkanes are valuable building blocks for the production of biopolyesters and biopolyamides. One of the key steps in producing these chemicals is the oxidation of ω-hydroxycarboxylic acids using alcohol dehydrogenases (e.g., ChnD of Acinetobacter sp. NCIMB 9871). However, the reaction and structural features of these enzymes remain mostly undiscovered. Thereby, we have investigated characteristics of ChnD based on enzyme kinetics, substrate-docking simulations, and mutation studies. Kinetic analysis revealed a distinct preference of ChnD for medium chain ω-hydroxycarboxylic acids, with the highest catalytic efficiency of 18.0 mMs for 12-hydroxydodecanoic acid among C6 to C12 ω-hydroxycarboxylic acids. The high catalytic efficiency was attributed to the positive interactions between the carboxyl group of the substrates and the guanidino group of two arginine residues (i.e., Arg62 and Arg266) in the substrate binding site. The ChnD_R62L variant showed the increased efficiency and affinity, particularly for fatty alcohols (i.e., C6-C10) and branched-chain fatty alcohols, such as 3-methyl-2-buten-1-ol. Overall, this study contributes to the deeper understanding of medium-chain primary aliphatic alcohol dehydrogenases and their applications for the production of industrially relevant chemicals such as α,ω-dicarboxylic acids, ω-aminoalkanoic acids, and α,ω-diaminoalkanes from renewable biomass. 10.1016/j.jbiotec.2024.06.008
Comparative analysis of the fatty acid profiles in goat milk during different lactation periods and their interactions with volatile compounds and metabolites. Food chemistry This study aimed to compare the composition of fatty acids in goat milk during lactation with human milk, as well as analyze the differences in their interaction with odor and metabolites. Polyunsaturated fatty acids content was higher in human milk, while odd-chain, branched-chain, and monounsaturated fatty acids content were higher in goat milk with a decreasing trend during lactation. PUFAs in human milk undergo auto-oxidation to produce aldehydes (hexanal), giving it a mild aroma. Butyric acid in goat colostrum mediates the synthesis and auto-oxidation of PUFA, while taurine mediated the hydrolysis of amino acids. They produce a furanone compound (2(5H)-furanone) with a buttery flavor. The presence of butyric acid in goat transitional milk had an impact on flavor and metabolites. The medium chain fatty acid composition of the goat mature milk was affected by nucleic acid compounds, which then oxidized to produce methyl ketone (2-nonanone), giving it an unpleasant flavor. 10.1016/j.foodchem.2024.140427
LC-MS/MS-based phospholipid profiling of plant-pathogenic bacteria with tailored separation of methyl-branched species. Analytical and bioanalytical chemistry Plant-pathogenic bacteria are one of the major constraints on agricultural yield. In order to selectively treat these bacteria, it is essential to understand the molecular structure of their cell membrane. Previous studies have focused on analyzing hydrolyzed fatty acids (FA) due to the complexity of bacterial membrane lipids. These studies have highlighted the occurrence of branched-chain fatty acids (BCFA) alongside normal-chain fatty acids (NCFA) in many bacteria. As several FA are bound in the intact phospholipids of the bacterial membrane, the presence of isomeric FA complicates lipid analysis. Furthermore, commercially available reference standards do not fully cover potential lipid isomers. To address this issue, we have developed a reversed-phase high-performance liquid chromatography (RP-HPLC) method with tandem mass spectrometry (MS/MS) to analyze the phospholipids of various plant-pathogenic bacteria with a focus on BCFA containing phospholipids. The study revealed the separation of three isomeric phosphatidylethanolamines (PE) depending on the number of bound BCFA to NCFA. The validation of the retention order was based on available reference standards in combination with the analysis of hydrolyzed fatty acids through gas chromatography with mass spectrometry (GC/MS) after fractionation. Additionally, the transferability of the retention order to other major lipid classes, such as phosphatidylglycerols (PG) and cardiolipins (CL), was thoroughly examined. Using the information regarding the retention behavior, the phospholipid profile of six plant-pathogenic bacteria was structurally elucidated. Furthermore, the developed LC-MS/MS method was used to classify the plant-pathogenic bacteria based on the number of bound BCFA in the phospholipidome. 10.1007/s00216-024-05451-1
Lipid Profile of Plant-Based Milk Alternatives (PBMAs) and Cow's Milk: A Comparison. Journal of agricultural and food chemistry Some consumers are replacing cow's milk with plant-based milk alternatives (PBMAs). The present study aimed to characterize the lipid profiles of cow's milk ( = 60) and PBMA types (soya, oat, rice, almond, coconut, and hazelnut; = 10 per type). Significant differences were found in the fatty acid (FA) profiles of PBMAs and milk, particularly in FA diversity (15 FAs in PBMAs vs 54 FAs in milk) and the proportion of prime FA groups. The FA profile of coconut was dominated by saturated FAs (SFA), whereas monounsaturated FAs (MUFA) or polyunsaturated FAs (PUFA) were dominant in the remaining PBMA types. Cholesterol was not detected in any PBMA type. The FA profile of milk FAs was dominated by SFA; however, different individual SFA have varying health outcomes. Additionally, milk contains some FA groups with health-promoting properties, such as methyl-branched-chain FAs (BCFA) and conjugated linoleic acid (CLA), both of which are absent in PBMAs. 10.1021/acs.jafc.4c03091
Developmental toxicity and estrogenic activity of antimicrobial phenolic-branched fatty acids using simulations and and bioassay. Frontiers in toxicology Due to the growing safety and environmental concerns associated with biocides, phenolic-soy branched chain fatty acids (phenolic-soy BCFAs) are synthesized as new bio-based antimicrobial agents. Safety evaluation is essential before the wide adoption of these new antimicrobial products. This study was initiated to evaluate the safety of four phenolic-soy BCFAs (with phenol, thymol, carvacrol, or creosote branches). Methyl-branched iso-oleic acid, phenol, and creosote were included in the study as controls. toxicity simulation tools predicted that the phenolic BCFAs had much higher toxicities to aquatic organisms than free phenolics did, while the opposite was predicted for rats. The developmental toxicity of four phenolic-soy BCFAs was assessed using an chicken embryonic assay. Results showed that creosote-soy BCFA had much lower mortality rates than creosote at the same dosages. Additionally, creosote-soy BCFA and methyl-branched iso-oleic acid induced minimal estrogenic activity in the concentration range of 10 nM - 1 µM. Carvacrol-soy BCFA treatments significantly increased ( < 0.05) oxidative stress levels with higher thiobarbituric acid reactive substances in the livers of chicken embryos. Altogether, the phenolic-soy BCFAs, especially creosote-soy BCFA, reported in this study are potentially promising and safer bio-based antimicrobial products. 10.3389/ftox.2024.1380485
Determination of double bond configuration of 2-hydroxy-fatty acids and emendation of cellular fatty acid composition of Aureispira marina and Aureispira maritima. The Journal of general and applied microbiology Aureispira marina is a marine bacterium with gliding motility isolated from the southern coastline of Thailand. It contained ceramide as a major cellular lipid composed of saturated or unsaturated branched chain 2-hydroxy-fatty acid and sphingosine. The structure of unsaturated 2-hydroxy-fatty acid was investigated in our previous study, but the geometric configuration of the double bond remained unclear. In the present study, 14-methyl-∆-pentadecenol (∆-iso-C-ol) was prepared from D-2-hydroxy-15-methyl-∆-hexadecenoic acid (D-2-OH-∆-iso-C) of the ceramide component, and analyzed by H and C NMR in comparison with ∆-trans-hexadecenol (∆-trans-n-C-ol) derived from commercially available D-sphingosine. From the coupling constants of protons in the double bond and the chemical shift value of allylic carbon, the configuration of the double bond was determined as trans. Since the structure of 2-hydroxy-fatty acids was clarified, cellular fatty acids of A. marina and A. maritima, another species of the genus Aureispira, were reexamined, and the description on the cellular fatty acid composition of the genus Aureispira in the previous papers (Hosoya et al., 2006, Int. J. System. Evol. Microbiol., 56, 2931-2935; Hosoya et al., 2007, Int. J. System. Evol. Microbiol., 57, 1948-1951) lacking the description of 2-hydroxy-fatty acids was emended. 10.2323/jgam.2024.09.001
A Prospective Analysis of Per- and Polyfluoroalkyl Substances from Early Pregnancy to Delivery in the Atlanta African American Maternal-Child Cohort. Environmental health perspectives BACKGROUND:Longitudinal trends in per- and polyfluoroalkyl substances (PFAS) serum concentrations across pregnancy have not been thoroughly examined, despite evidence linking prenatal PFAS exposures with adverse birth outcomes. OBJECTIVES:We sought to characterize longitudinal PFAS concentrations across pregnancy and to examine the maternal-fetal transfer ratio among participants in a study of risk and protective factors for adverse birth outcomes among African Americans. METHODS:In the Atlanta African American Maternal-Child cohort (2014-2020), we quantified serum concentrations of four PFAS in 376 participants and an additional eight PFAS in a subset of 301 participants during early (8-14 weeks gestation) and late pregnancy (24-30 weeks gestation). Among these, PFAS concentrations were also measured among 199 newborns with available dried blood spot (DBS) samples. We characterized the patterns, variability, and associations in PFAS concentrations at different time points across pregnancy using intraclass correlation coefficients (ICCs), maternal-newborn pairs transfer ratios, linear mixed effect models, and multivariable linear regression, adjusting for socioeconomic and prenatal predictors. RESULTS:Perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) were detected in of maternal samples, with PFHxS and PFOS having the highest median concentrations. We observed high variability in PFAS concentrations across pregnancy time points (). All median PFAS concentrations increased from early to late pregnancy, except for PFOA and N-methyl perfluorooctane sulfonamido acetic acid (NMFOSAA), which decreased [paired -test for all PFAS except for PFOA and perfluorobutane sulfonic acid (PFBS)]. Prenatal serum PFAS were weakly to moderately correlated with newborn DBS PFAS ( ). The median maternal-fetal PFAS transfer ratio was lower for PFAS with longer carbon chains. After adjusting for socioeconomic and prenatal predictors, in linear mixed effect models, the adjusted mean PFAS concentrations significantly increased during pregnancy, except for PFOA. In multivariable linear regression, PFAS concentrations in early pregnancy significantly predicted the PFAS concentrations in late pregnancy and in newborns. DISCUSSION:We found that the concentrations of most PFAS increased during pregnancy, and the magnitude of variability differed by individual PFAS. Future studies are needed to understand the influence of within-person PFAS variability during and after pregnancy on birth outcomes. https://doi.org/10.1289/EHP14334. 10.1289/EHP14334
Biosynthesis of branched-chain fatty acids in Bacillus subtilis. A decarboxylase is essential for branched-chain fatty acid synthetase. Oku H,Kaneda T The Journal of biological chemistry Branched long-chain fatty acids of the iso and anteiso series are synthesized in many bacteria from the branched-chain alpha-keto acids of valine, leucine, and isoleucine after their decarboxylation followed by chain elongation. Two distinct branched-chain alpha-keto acid (BCKA) and pyruvate decarboxylases, which are considered to be responsible for primer synthesis, were detected in, and purified in homogenous form from Bacillus subtilis 168 strain by procedures including ammonium sulfate fractionation and chromatography on ion exchange, reversed-phase, and gel absorption columns. The chemical and catalytic properties of the two decarboxylases were studied in detail. The removal of BCKA decarboxylase, using chromatographic fractionation, from the fatty acid synthetase significantly reduced its activity. The synthetase activity was completely lost upon immunoprecipitation of the decarboxylase. The removal of pyruvate decarboxylase by the above two methods, however, did not affect any activity of the fatty acid synthetase. Thus, BCKA decarboxylase, but not pyruvate decarboxylase, is essential for the synthesis of branched-chain fatty acids. The very high affinity of BCKA decarboxylase toward branched-chain alpha-keto acids is responsible for its function in fatty acid synthesis.
A simple and rapid enzymatic assay for the branched-chain alpha-ketoacid dehydrogenase complex using high-performance liquid chromatography. Tajima G,Yofune H,Bahagia Febriani A D,Nishimura Y,Ono H,Sakura N Journal of inherited metabolic disease Maple syrup urine disease (MSUD) is caused by a congenital defect of the branched-chain alpha-ketoacid dehydrogenase complex (BCKADC), and is one of the target disorders in newborn screening. However, it is not always easy to confirm the diagnosis; conventional methods of enzyme assay require cell culture, isolation of mitochondria, or radioisotope-labelled reagents, and disease-causing mutations can exist in any of the genes encoding the three enzyme subunits. To realize a practical test for diagnostic confirmation, we developed a simple and rapid enzymatic assay for BCKADC. In this procedure, the production of isovaleryl-CoA from 2-ketoisocaproic acid was measured using high-performance liquid chromatography. Detection of the BCKADC product was significantly reproducible depending on concentration of the substrates. We applied the assay to two patients with MSUD and demonstrated pathologically low levels of residual activity in both subjects. These results indicate that our method is a practical and sensitive assay for BCKADC, and that it can be a useful adjunct in newborn screening for MSUD. 10.1023/b:boli.0000042988.31581.ed
Chemical Synthesis of 8-Methyl-6-Nonenoyl-CoA and Functional Expression Unravel Capsaicin Synthase Activity Encoded by the Locus. Molecules (Basel, Switzerland) Capsaicin, produced by diverse species, is among the world's most popular spices and of considerable pharmaceutical relevance. Although the capsaicinoid biosynthetic pathway has been investigated for decades, several biosynthetic steps have remained partly hypothetical. Genetic evidence suggested that the decisive capsaicin synthase is encoded by the locus. Yet, the genetic evidence of the locus was never corroborated by functionally active capsaicin synthase that presumably catalyzes an amide bond formation between 8-methyl-6-nonenoyl-CoA derived from branched-chain amino acid biosynthesis and vanilloylamine derived from the phenylpropanoid pathway. In this report, we demonstrate the enzymatic activity of a recombinant capsaicin synthase encoded by , functionally expressed in , and provide information on its substrate specificity and catalytic properties. Recombinant capsaicin synthase is specific for selected aliphatic CoA-esters and highly specific for vanilloylamine. Partly purified from , the recombinant active enzyme is a monomeric protein of 51 kDa that is independent of additional co-factors or associated proteins, as previously proposed. These data can now be used to design capsaicin synthase variants with different properties and alternative substrate preferences. 10.3390/molecules27206878
Metabolic engineering of Saccharomyces cerevisiae for production of fatty acid short- and branched-chain alkyl esters biodiesel. Teo Wei Suong,Ling Hua,Yu Ai-Qun,Chang Matthew Wook Biotechnology for biofuels BACKGROUND:Biodiesel is a mixture of fatty acid short-chain alkyl esters of different fatty acid carbon chain lengths. However, while fatty acid methyl or ethyl esters are useful biodiesel produced commercially, fatty acid esters with branched-chain alcohol moieties have superior fuel properties. Crucially, this includes improved cold flow characteristics, as one of the major problems associated with biodiesel use is poor low-temperature flow properties. Hence, microbial production as a renewable, nontoxic and scalable method to produce fatty acid esters with branched-chain alcohol moieties from biomass is critical. RESULTS:We engineered Saccharomyces cerevisiae to produce fatty acid short- and branched-chain alkyl esters, including ethyl, isobutyl, isoamyl and active amyl esters using endogenously synthesized fatty acids and alcohols. Two wax ester synthase genes (ws2 and Maqu_0168 from Marinobacter sp.) were cloned and expressed. Both enzymes were found to catalyze the formation of fatty acid esters, with different alcohol preferences. To boost the ability of S. cerevisiae to produce the aforementioned esters, negative regulators of the INO1 gene in phospholipid metabolism, Rpd3 and Opi1, were deleted to increase flux towards fatty acyl-CoAs. In addition, five isobutanol pathway enzymes (Ilv2, Ilv5, Ilv3, Aro10, and Adh7) targeted into the mitochondria were overexpressed to enhance production of alcohol precursors. By combining these engineering strategies with high-cell-density fermentation, over 230 mg/L fatty acid short- and branched-chain alkyl esters were produced, which is the highest titer reported in yeast to date. CONCLUSIONS:In this work, we engineered the metabolism of S. cerevisiae to produce biodiesels in the form of fatty acid short- and branched-chain alkyl esters, including ethyl, isobutyl, isoamyl and active amyl esters. To our knowledge, this is the first report of the production of fatty acid isobutyl and active amyl esters in S. cerevisiae. Our findings will be useful for engineering S. cerevisiae strains toward high-level and sustainable biodiesel production. 10.1186/s13068-015-0361-5
Lipoic acid-dependent oxidative catabolism of alpha-keto acids in mitochondria provides evidence for branched-chain amino acid catabolism in Arabidopsis. Plant physiology Lipoic acid-dependent pathways of alpha-keto acid oxidation by mitochondria were investigated in pea (Pisum sativum), rice (Oryza sativa), and Arabidopsis. Proteins containing covalently bound lipoic acid were identified on isoelectric focusing/sodium dodecyl sulfate-polyacrylamide gel electrophoresis separations of mitochondrial proteins by the use of antibodies raised to this cofactor. All these proteins were identified by tandem mass spectrometry. Lipoic acid-containing acyltransferases from pyruvate dehydrogenase complex and alpha-ketoglutarate dehydrogenase complex were identified from all three species. In addition, acyltransferases from the branched-chain dehydrogenase complex were identified in both Arabidopsis and rice mitochondria. The substrate-dependent reduction of NAD(+) was analyzed by spectrophotometry using specific alpha-keto acids. Pyruvate- and alpha-ketoglutarate-dependent reactions were measured in all three species. Activity of the branched-chain dehydrogenase complex was only measurable in Arabidopsis mitochondria using substrates that represented the alpha-keto acids derived by deamination of branched-chain amino acids (Val [valine], leucine, and isoleucine). The rate of branched-chain amino acid- and alpha-keto acid-dependent oxygen consumption by intact Arabidopsis mitochondria was highest with Val and the Val-derived alpha-keto acid, alpha-ketoisovaleric acid. Sequencing of peptides derived from trypsination of Arabidopsis mitochondrial proteins revealed the presence of many of the enzymes required for the oxidation of all three branched-chain amino acids. The potential role of branched-chain amino acid catabolism as an oxidative phosphorylation energy source or as a detoxification pathway during plant stress is discussed. 10.1104/pp.103.035675
Purification and properties of an alpha-methylacyl-CoA racemase from rat liver. Schmitz W,Fingerhut R,Conzelmann E European journal of biochemistry The (R)- and (S)-isomers of alpha-methyl-branched fatty acids were shown to be rapidly interconverted as coenzyme A thioesters, by an alpha-methylacyl-CoA racemase. The enzyme was purified some 5600-fold from rat liver, to apparent homogeneity. It is a monomer of 45 kDa with an isolectric point of pH 6.1 and is optimally active between pH 6 and pH 7. It acts only on coenzyme A thioesters, not on free fatty acids, and accepts as substrates a wide range of alpha-methylacyl-CoAs, including pristanoyl-CoA and trihydroxycoprostanoyl-CoA (an intermediate in bile acid synthesis), but neither 3-methyl-branched nor linear-chain acyl-CoAs. The racemase catalyzes a rapid exchange of the H atom in the alpha-position of the fatty acid against a proton from water, indicating that the mechanism involves abstraction of a proton. Based on this observation, a very sensitive and convenient radiometric assay, with 2-methyl[2-(3)H]acyl-CoAs as substrates, was developed. The enzyme was inactivated by micromolar concentrations of Hg2+ and to a lesser extent by Cu2+ but not by iodoacetamide and only slightly by N-ethylmaleimide and thimerosal. 10.1111/j.1432-1033.1994.tb18870.x
Demonstration of a new mammalian isoleucine catabolic pathway yielding an Rseries of metabolites. Mamer O A,Tjoa S S,Scriver C R,Klassen G A The Biochemical journal 1. Normal human urine contains small amounts (less than 4 mg/g of creatinine) of 2-ethylhydracrylic acid, formed, we believe, by a previously undisclosed endogenous catabolic pathway for the oxidation of a newly described series of R metabolites of isoleucine. 2. Urinary excretion of 2-ethylhydracrylic acid is variably increased in defects of isoleucine oxidation at distal steps in the catabolic pathway (3-oxoacyl-CoA thiolase deficiency and methylmalonyl-CoA mutase deficiency) and is diminished when proximal steps of the oxidative pathway are blocked as in branched-chain oxo acid decarboxylase deficiency ('maple-syrup-urine' disease). 3. Precursors of R-pathway metabolites [R(-)-2-methylbutyrate and 2-ethylacrylate ] lead to increased 2-ethylhydracrylate excretion in the mammal(rat, rabbit and dog); the corresponding S metabolites [S(+)-2-methylbutyric acid and tiglic acid ], when given in equimolar amounts, have little effect on its excretion, suggesting that little or no interconversion between S and R metabolites occurs in vivo. 4. Studies with 2H-labelled precursors indicate that conversion of R 2-methylbutyrate into 2-ethylhydracrylic acid occurs by a direct pathway (apparently via 2-ethylacrylic acid). 5. The further oxidation of 2-ethylhydracrylic acid to ethylmalonic acid was demonstrated, and may be analogous to S-metabolite oxidation via methyl malonate. 6. Valine metabolites do not interact with the R=isoleucine pathway under the conditions of these experiments in vivo. 10.1042/bj1600417a
Reduced transaminase B (IlvE) activity caused by the lack of yjgF is dependent on the status of threonine deaminase (IlvA) in Salmonella enterica serovar Typhimurium. Schmitz George,Downs Diana M Journal of bacteriology The YjgF/YER057c/UK114 family is a highly conserved class of proteins that is represented in the three domains of life. Thus far, a biochemical function demonstrated for these proteins in vivo or in vitro has yet to be defined. In several organisms, strains lacking a YjgF homolog have a defect in branched-chain amino acid biosynthesis. This study probes the connection between yjgF and isoleucine biosynthesis in Salmonella enterica. In strains lacking yjgF the specific activity of transaminase B, catalyzing the last step in the synthesis of isoleucine, was reduced. In the absence of yjgF, transaminase B activity could be restored by inhibiting threonine deaminase, the first enzymatic step in isoleucine biosynthesis. Strains lacking yjgF showed an increased sensitivity to sulfometruron methyl, a potent inhibitor of acetolactate synthase. Based on work described here and structural reports in the literature, we suggest a working model in which YjgF has a role in protecting the cell from toxic effects of imbalanced ketoacid pools. 10.1128/JB.186.3.803-810.2004
Studies on the activation and inactivation of the branched chain alpha-keto acid dehydrogenase in the perfused rat heart. Waymack P P,DeBuysere M S,Olson M S The Journal of biological chemistry Evidence for a reversible process resulting in stable activated and inactivated states of the mitochondrial branched chain alpha-keto acid dehydrogenase complex in isolated perfused rat heart is presented. The inactivation process is mediated by pyruvate infusion, while activation (up to 18-fold) is facilitated by branched chain alpha-keto acid substrates. The low activity state of the branched chain complex characteristic of freshly excised rat hearts could be maintained by infusion of either pyruvate or glucose. Activation of the complex in the perfused rat heart was achieved slowly by substrate-free perfusion, while rapid activation was accomplished by infusion of branched chain alpha-keto acids. The fully activated enzyme complex resulting from branched chain alpha-keto acid infusion subsequently could be inactivated maximally by infusion of pyruvate alone or intermediate degrees of inactivation could be produced by certain ratios of co-infused pyruvate and branched chain alpha-keto acid. alpha-Ketoisocaproate was an order of magnitude more effective than alpha-keto isovalerate either in preventing inactivation or in stimulating the opposing activation process when co-infused with pyruvate. The mitochondrial pyruvate transport inhibitor, alpha-cyanocinnamate, effectively prevented inactivation of the complex by infused pyruvate. Differential changes in the activation states of the branched chain alpha-keto acid dehydrogenase and pyruvate dehydrogenase complexes were evident when the two complexes were compared in apparently similar flux-inhibited (via octanoate infusion) and flux-stimulated (via dichloroacetate infusion) metabolic conditions. The differential effect of pyruvate concentration on the activity states of the two complexes was also well-defined. The results of the present study suggest distinct systems for the regulation of the activity of the two multienzyme complexes of interest. While our results argue neither for nor against an inactivation of the branched chain alpha-keto acid dehydrogenase complex by a protein kinase, the regulatory properties of such an intramitochondrial protein kinase may not be similar to the pyruvate dehydrogenase kinase. The mechanistic nature of the suggested novel regulatory system concerned with the pyruvate-mediated inactivation of the branched chain alpha-keto acid activation cannot be inferred at the present time.
Activation of branched-chain alpha-ketoacid dehydrogenase complex by alpha-chloroisocaproate in normal and enzyme-deficient fibroblasts. Toshima K,Kuroda Y,Yokota I,Naito E,Ito M,Watanabe T,Takeda E,Miyao M Clinica chimica acta; international journal of clinical chemistry A method has been developed for the activation of the branched-chain alpha-ketoacid dehydrogenase complex by alpha-chloroisocaproate, an inhibitor of branched-chain alpha-ketoacid dehydrogenase kinase in human cultured skin fibroblasts. The enzyme could be activated by pretreating the cells with alpha-chloroisocaproate before they were disrupted for measurement of the activity. After this treatment, the activity was 2- to 3-fold that of untreated cells (24.8-81.4 pmol/min per mg protein). The enzyme activity in fibroblasts from a patient with maple syrup urine disease was measured by this procedure. After activation by alpha-chloroisocaproate, the activity of fibroblasts from the patient was only 10-14 pmol/min per mg protein (10% of that of controls), and was almost the same as that of the untreated cells from this patient. These results show that it is important to consider the activation state of branched-chain alpha-ketoacid dehydrogenase complex when assaying it in disrupted cells. 10.1016/0009-8981(85)90070-1
Natural variation in arsenic toxicity is explained by differences in branched chain amino acid metabolism. Zdraljevic Stefan,Fox Bennett William,Strand Christine,Panda Oishika,Tenjo Francisco J,Brady Shannon C,Crombie Tim A,Doench John G,Schroeder Frank C,Andersen Erik C eLife We find that variation in the gene underlies natural differences in responses to the toxin arsenic. This gene encodes the E2 subunit of the branched-chain α-keto acid dehydrogenase (BCKDH) complex, a core component of branched-chain amino acid (BCAA) metabolism. We causally linked a non-synonymous variant in the conserved lipoyl domain of DBT-1 to differential arsenic responses. Using targeted metabolomics and chemical supplementation, we demonstrate that differences in responses to arsenic are caused by variation in iso-branched chain fatty acids. Additionally, we show that levels of branched chain fatty acids in human cells are perturbed by arsenic treatment. This finding has broad implications for arsenic toxicity and for arsenic-focused chemotherapeutics across human populations. Our study implicates the BCKDH complex and BCAA metabolism in arsenic responses, demonstrating the power of natural genetic diversity to identify novel mechanisms by which environmental toxins affect organismal physiology. Editorial note:This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter). 10.7554/eLife.40260
Structure of the O-specific polysaccharide from the lipopolysaccharide of Citrobacter gillenii O11, strain PCM 1540. Katzenellenbogen Ewa,Kocharova Nina A,Zatonsky George V,Bogulska Maria,Rybka Jacek,Gamian Andrzej,Shashkov Alexander S,Knirel Yuriy A Carbohydrate research The O-specific polysaccharide of the lipopolysaccharide of Citrobacter gillenii PCM 1540 (serogroup O11) consists of D-Glc, D-Man, D-GalNAc, D-GlcNAc, 2-acetamido-2,6-dideoxy-D-galactose (D-FucNAc) and O-acetyl groups in the ratios 2:1:1:1:1:1. On the basis of sugar and methylation analyses and Smith-degradation along with 1D and 2D 1H and 13C NMR spectroscopy, the following structure of the branched hexasaccharide repeating unit was established: [structure: see text]. Citrobacter werkmanii PCM 1541 belonging to the same serogroup O11 was found to have an R-form lipopolysaccharide devoid of the O-specific polysaccharide.
Metabolic profiling of Medicago truncatula cell cultures reveals the effects of biotic and abiotic elicitors on metabolism. Broeckling Corey D,Huhman David V,Farag Mohamed A,Smith Joel T,May Gregory D,Mendes Pedro,Dixon Richard A,Sumner Lloyd W Journal of experimental botany GC-MS-based metabolite profiling was used to analyse the response of Medicago truncatula cell cultures to elicitation with methyl jasmonate (MeJa), yeast elicitor (YE), or ultraviolet light (UV). Marked changes in the levels of primary metabolites, including several amino acids, organic acids, and carbohydrates, were observed following elicitation with MeJa. A similar, but attenuated response was observed following YE elicitation, whereas little response was observed following UV elicitation. MeJa induced the accumulation of the triterpene beta-amyrin, a precursor to the triterpene saponins, and LC-MS analysis confirmed the accumulation of triterpene saponins in MeJa-elicited samples. In addition, YE induced a slight, but significant accumulation of shikimic acid, an early precursor to the phenylpropanoid pathway, which was also demonstrated to be YE-inducible by LC-MS analyses. Correlation analyses of metabolite relationships revealed perturbation of the glycine, serine, and threonine biosynthetic pathway, and suggested the induction of threonine aldolase activity, an enzyme as yet uncharacterized from plants. Members of the branched chain amino acid pathway accumulated in a concerted fashion, with the strongest correlation being that between leucine and isoleucine (r2=0.941). While UV exposure itself had little effect on primary metabolites, the experimental procedure, as revealed by control treatments, induced changes in several metabolites which were similar to those following MeJa elicitation. Sucrose levels were lower in MJ- and YE-elicited samples compared with control samples, suggesting that a portion of the effects observed on the primary metabolic pool are a consequence of fundamental metabolic repartitioning of carbon resources rather than elicitor-specific induction. In addition, beta-alanine levels were elevated in all elicited samples, which, when viewed in the context of other elicitation responses, suggests the altered metabolism of coenzyme A and its esters, which are essential in secondary metabolism. 10.1093/jxb/eri058
Effect of alpha-ketoacid dehydrogenase phosphorylation on branched-chain amino acid metabolism in muscle. Hood D A,Terjung R L The American journal of physiology The regulation of leucine and valine metabolism was evaluated in skeletal muscle of perfused rat hindlimb. Control of the branched-chain alpha-ketoacid dehydrogenase (BCKADH) via phosphorylation was removed with 0.4 mM alpha-chloroisocaproate (CIC). CIC activated the BCKADH complex 13- to 26-fold and led to increased rates of leucine and valine uptake into muscle, transamination to the corresponding alpha-ketoacid, and leucine (3- to 4-fold) and valine (6-fold) decarboxylation but led to decreased rates of alpha-ketoacid efflux from muscle. Although the increased rates of branched-chain amino acid (BCAA) decarboxylation were extensive, they were far below the extent of BCKADH activation as measured in vitro, suggesting that factors other than BCKADH activation become dominant in controlling the flux through alpha-ketoacid decarboxylation in skeletal muscle in situ. When the BCKADH capacity of muscle was increased 70-90% by a training-induced increase in mitochondrial content, the same 13- to 26-fold activation of the complex by CIC led to a rate of BCAA decarboxylation, which was only marginally greater (10-20%; P less than 0.05) than that of normal muscle. In addition, increasing the energy demand via muscle contractions led to a significant increase in leucine decarboxylation in the presence of complete activation of BCKADH by dephosphorylation. Thus BCKADH phosphorylation-dephosphorylation plays an important though not exclusive role in modulating the rates of BCAA metabolism in skeletal muscle. Differences in valine and leucine metabolism were apparent as valine catabolism bolstered citric acid cycle contents by increasing malate in red muscle with high mitochondrial content.(ABSTRACT TRUNCATED AT 250 WORDS) 10.1152/ajpendo.1991.261.5.E628
Serum aromatic and branched-chain amino acids associated with NASH demonstrate divergent associations with serum lipids. de Mello Vanessa D,Sehgal Ratika,Männistö Ville,Klåvus Anton,Nilsson Emma,Perfilyev Alexander,Kaminska Dorota,Miao Zong,Pajukanta Päivi,Ling Charlotte,Hanhineva Kati,Pihlajamäki Jussi Liver international : official journal of the International Association for the Study of the Liver BACKGROUND & AIMS:Non-alcoholic fatty liver disease (NAFLD) has been associated with multiple metabolic abnormalities. By applying a non-targeted metabolomics approach, we aimed at investigating whether serum metabolite profile that associates with NAFLD would differ in its association with NAFLD-related metabolic risk factors. METHODS & RESULTS:A total of 233 subjects (mean ± SD: 48.3 ± 9.3 years old; BMI: 43.1 ± 5.4 kg/m ; 64 male) undergoing bariatric surgery were studied. Of these participants, 164 with liver histology could be classified as normal liver (n = 79), simple steatosis (SS, n = 40) or non-alcoholic steatohepatitis (NASH, n = 45). Among the identified fasting serum metabolites with higher levels in those with NASH when compared to those with normal phenotype were the aromatic amino acids (AAAs: tryptophan, tyrosine and phenylalanine), the branched-chain amino acids (BCAAs: leucine and isoleucine), a phosphatidylcholine (PC(16:0/16:1)) and uridine (all FDRp < 0.05). Only tryptophan was significantly higher in those with NASH compared to those with SS (FDRp < 0.05). Only the AAAs tryptophan and tyrosine correlated positively with serum total and LDL cholesterol (FDRp < 0.1), and accordingly, with liver LDLR at mRNA expression level. In addition, tryptophan was the single AA associated with liver DNA methylation of CpG sites known to be differentially methylated in those with NASH. CONCLUSIONS:We found that serum levels of the NASH-related AAAs and BCAAs demonstrate divergent associations with serum lipids. The specific correlation of tryptophan with LDL-c may result from the molecular events affecting LDLR mRNA expression and NASH-associated methylation of genes in the liver. 10.1111/liv.14743
Differential effect of dichloroacetate on branched-chain amino acid catabolism in perfused rat hindlimbs. Schadewaldt P,Radeck W,Staib W FEBS letters The effect of 1 mM and 5 mM dichloroacetate on the catabolism of branched-chain amino acids in isolated rat hindlimbs was investigated in perfusions with 0.5 mM 1-14C-labeled L-leucine or L-valine. The results demonstrate an increasing effect of dichloroacetate on the flux through skeletal muscle branched-chain 2-oxo acid dehydrogenase. A minor effect was observed with the high dichloroacetate concentration. Evidence is presented that this was essentially due to diminished pyruvate supply. 10.1016/0014-5793(85)80948-0
Effect of lipoic acid in a patient with defective activity of pyruvate dehydrogenase, 2-oxoglutarate dehydrogenase, and branched-chain keto acid dehydrogenase. Yoshida I,Sweetman L,Kulovich S,Nyhan W L,Robinson B H Pediatric research Lactic acidosis and accumulation of 3-hydroxybutyrate and other citric acid cycle intermediates were found in an infant with a lethal syndrome of metabolic acidosis and renal tubular acidosis. Nevertheless, the patient was relatively well for 4 mo of life. The activity of the pyruvate dehydrogenase complex, 2-oxoglutarate dehydrogenase, and branched-chain keto acid dehydrogenase were all reduced to levels 9 to 29% of control. In contrast, the activity of lipoamide dehydrogenase was normal. The conversion of 1-14C-leucine and 1-14C-valine to 14CO2 and of U-L-14C-valine to its major metabolic product 3-hydroxyisobutyric acid by fibroblasts derived from the patient was less than 5% of control. Cultivation of the patient's fibroblasts in medium enriched with lipoic acid markedly improved these in vitro conversions of leucine and valine. 10.1203/00006450-199001000-00020
Design, synthesis, and in vitro testing of alpha-methylacyl-CoA racemase inhibitors. Carnell Andrew J,Hale Ian,Denis Simone,Wanders Ronald J A,Isaacs William B,Wilson Brice A,Ferdinandusse Sacha Journal of medicinal chemistry The enzyme alpha-methylacyl-CoA racemase (AMACR) is overexpressed in prostate, colon, and other cancers and has been partially validated as a potential therapeutic target by siRNA knockdown of the AMACR gene. Analogs of the natural substrate branched chain alpha-methylacyl coenzyme A esters, possessing one or more beta-fluorine atoms, have been synthesized using Wittig, conjugate addition, and asymmetric aldol reactions and found to be reversible competitive inhibitors. Each diastereomer of the previously reported inhibitor ibuprofenoyl-CoA was also tested. The compounds had Ki values of 0.9-20 microM and are the most potent inhibitors yet known. The presence of beta-fluorine on the alpha-methyl group or the acyl chain results in a significant lowering of the Ki value compared with nonfluorinated analogs, and this is attributed to a lowering of the pKa of the alpha-proton, facilitating enolization and binding. Several of the CoA ester inhibitors were formed by incubating the free carboxylic acid precursors with cell free extracts and CoA. alpha-Trifluoromethyltetradecanoic acid, the precursor to the most potent inhibitor, was shown to inhibit growth of cancer cell lines PC3, CWR22 Rv1, and Du145 in a dose-dependent manner and could be related to the expression level of AMACR. 10.1021/jm0702377
Branched Chain Lipid Metabolism As a Determinant of the -Acyl Variation of Natural Products. Price Neil P J,Jackson Michael A,Hartman Trina M,Brändén Gisela,Ek Margareta,Koch Aaron A,Kennedy Paul D ACS chemical biology Branched-chain fatty acids (BCFA) are encountered in Gram-positive bacteria, but less so in other organisms. The bacterial BCFA in membranes are typically saturated, with both odd- and even-numbered carbon chain lengths, and with methyl branches at either the ω-1 () or ω-2 () positions. The acylation with BCFA also contributes to the structural diversity of microbial natural products and potentially modulates biological activity. For the tunicamycin (TUN) family of natural products, the toxicity toward eukaryotes is highly dependent upon -acylation with -2,3-unsaturated BCFA. The loss of the 2,3-unsaturation gives modified TUN with reduced eukaryotic toxicity but crucially with retention of the synergistic enhancement of the β-lactam group of antibiotics. Here, we infer from genomics, mass spectrometry, and deuterium labeling that the -2,3-unsaturated TUN variants and the saturated cellular lipids found in TUN-producing are derived from the same pool of BCFA metabolites. Moreover, non-natural primers of BCFA metabolism are selectively incorporated into the cellular lipids of TUN-producing and concomitantly produce structurally novel -branched TUN -acyl variants. 10.1021/acschembio.0c00799
Sex Pheromone of the Azalea Mealybug: Absolute Configuration and Kairomonal Activity. Journal of chemical ecology The sex pheromone of the azalea mealybug, Crisicoccus azaleae (Tinsley, 1898) (Hemiptera: Pseudococcidae), includes esters of a methyl-branched medium-chain fatty acid, ethyl and isopropyl (E)-7-methyl-4-nonenoate. These compounds are exceptional among mealybug pheromones, which are commonly monoterpenes. Determination of the absolute configuration is challenging, because both chromatographic and spectrometric separations of stereoisomers of fatty acids with a methyl group distant from the carboxyl group are difficult. To solve this problem, we synthesized the enantiomers via the Johnson-Claisen rearrangement to build (E)-4-alkenoic acid by using (R)- and (S)-3-methylpentanal as chiral blocks, which were readily available from the amino acids L-(+)-alloisoleucine and L-(+)-isoleucine, respectively. Each pure enantiomer, as well as the natural pheromone, was subsequently derivatized with a highly potent chiral labeling reagent used in the Ohrui-Akasaka method. Through NMR spectral comparisons of these derivatives, the absolute configuration of the natural pheromone was determined to be S. Field-trap bioassays showed that male mealybugs were attracted more to (S)-enantiomers and preferred the natural stereochemistry. Moreover, the synthetic pheromones attracted Anagyrus wasps, indicating that the azalea mealybug pheromone has kairomonal activity. 10.1007/s10886-024-01473-2
Inhibition of branched chain alpha-ketoacid dehydrogenase kinase activity by alpha-chloroisocaproate. Harris R A,Paxton R,DePaoli-Roach A A The Journal of biological chemistry alpha-Chloroisocaproate has been shown to inhibit phosphorylation and inactivation of rabbit liver branched chain alpha-ketoacid dehydrogenase complex. Phosphorylation of pyruvate dehydrogenase was also inhibited by this alpha-ketoisocaproate analog, but phosphorylation of branched chain alpha-ketoacid dehydrogenase was much more sensitive than phosphorylation of pyruvate dehydrogenase (I50 values of 7.5 and 675 microM, respectively). Phosphorylation of glycogen synthase by six other protein kinases was not inhibited by alpha-chloroisocaproate (1 mM). Although less sensitive than phosphorylation of the complex, branched chain alpha-ketoacid dehydrogenase was also found inhibited by alpha-chloroisocaproate. The latter inhibition was competitive with respect to the alpha-ketoacid substrates of the dehydrogenase (Ki values of approximately 0.5 mM). alpha-Chloroisocaproate greatly stimulated the capacity of the perfused rat heart to decarboxylate [1-14C]leucine and promoted conversion of practically all (99%) of the complex into the active form.
Regulatory and biosynthetic effects of the bkd gene clusters on the production of daptomycin and its analogs A21978C. Luo Shuai,Chen Xin-Ai,Mao Xu-Ming,Li Yong-Quan Journal of industrial microbiology & biotechnology Daptomycin is a cyclic lipopeptide antibiotic produced by Streptomyces roseosporus in an acidic peptide complex A21978C. In this complex, A21978C is most abundant and contains branched-chain fatty acyl groups, while daptomycin has a straight decanoic acyl group. The branched-chain α-keto acid dehydrogenase complex (BCDH complex), encoded by bkd gene clusters in Streptomyces, is responsible for the early step of converting branched-chain amino acids into branched-chain fatty acids. In a daptomycin industrial producer S. roseosporus L30, two alleles of bkd gene clusters, bkdA1B1C1/bkdA2B2C2, and a regulatory gene bkdR located upstream of bkdA2B2C2 are identified. We show that BkdR positively regulated bkdA2B2C2 expression and was negatively auto-regulated, but is not directly involved in regulation of daptomycin gene cluster expression. However, BkdR is required for both daptomycin and A21978C production. Furthermore, deletion of bkdA2B2C2 only led to partial reduction of A21978C production, while the ΔbkdA1B1C1 mutant shows very weak production of A21978C, and the double bkd mutant has a similar production profile as the single ΔbkdA1B1C1 mutant, suggesting that bkdA1B1C1 gene cluster plays a dominant role in branched-chain fatty acid biosynthesis. So we reveal a unique regulatory function of BkdR and genetic engineered a bkd null strain for daptomycin production with reduced impurities. 10.1007/s10295-018-2011-y
Modulating acetate ester and higher alcohol production in Saccharomyces cerevisiae through the cofactor engineering. Hong Kun-Qiang,Fu Xiao-Meng,Dong Sheng-Sheng,Xiao Dong-Guang,Dong Jian Journal of industrial microbiology & biotechnology Flavor production by esters or by higher alcohols play a key role in the sensorial quality of fermented alcoholic beverages. In Saccharomyces cerevisiae cells, the syntheses of esters and higher alcohols are considerably influenced by intracellular CoA levels catalyzed by pantothenate kinase. In this work, we examined the effects of cofactor CoA and acetyl-CoA synthesis on the metabolism of esters and higher alcohols. Strains 12α-BAP2 and 12α+ATF1 where generated by deleting and overexpressing BAP2 (encoded branched-chain amino acid permease) and ATF1 (encoded alcohol acetyl transferases), respectively, in the parent 12α strains. Then, 12α-BAP2+CAB1 and 12α-BAP2+CAB3 strains were obtained by overexpressing CAB1 (encoded pantothenate kinase Cab1) and CAB3 (encoded pantothenate kinase Cab3) in the 12α-BAP2 strain, and 12α-BAP2+CAB1+ATF1 and 12α-BAP2+CAB3+ATF1 were generated by overexpressing ATF1 in the pantothenate kinase overexpression strains. The acetate ester level in 12α-BAP2 was slightly changed relative to that in the control strain 12α, whereas the acetate ester levels in 12α-BAP2+CAB1, 12α-BAP2+CAB3, 12α-BAP2+CAB1+ATF1, and 12α-BAP2+CAB3+ATF1 were distinctly increased (44-118% for ethyl acetate and 18-57% for isoamyl acetate). The levels of n-propanol, methyl-1-butanol, isopentanol, isobutanol, and phenethylol levels were changed and varied among the six engineered strains. The levels of acetate esters and higher alcohols can be modulated by changing the CoA and acetyl-CoA levels. The method proposed in this work supplies a practical means of breeding yeast strains by modulating acetate ester and higher alcohol production. 10.1007/s10295-019-02176-4
Maple syrup urine disease: analysis of branched chain ketoacid decarboxylation in cultured fibroblasts. Wendel U,Wentrup H,Rüdiger H W Pediatric research Kinetic data are presented for the decarboxylation of branched chain alpha-ketoacids (BCKA) by intact human fibroblasts. Cultured cells of normal individuals and nine patients with different clinical pictures of maple syrup urine disease (MSUD) are studied with both alpha-ketoisocaproic acid (2-oxo-4-methylpentanoic acid (KIC)) and alpha-ketoisovaleric acid (2-oxo-3-methylbutanoic acid (KIVA)) as substrates. One normal cell strain and one patient cell strain is analyzed with alpha-keto-beta-methyl-n-valeric acid (2-oxo-3-methylpentanoic acid (MEVA)) as a substrate. A biphasic degradation kinetic for each BCKA is obtained for normal control subjects. The component with higher substrate affinity is affected in MSUD: for KIC the normally hyperbolic substrate curve is changed to sigmoid shape, for KIVA and MEVA as substrates this component is not detectable at all. Considering qualitative aspects of the BCKA decarboxylation kinetics intact fibroblasts yield the same results as our recent studies with the decarboxylase moieties of partially purified kidney BCKA dehydrogenase of normal individuals and one patient with classic MSUD (27). The decarboxylation velocities for normal and patient fibroblasts with one exception differ widely at low but not at high substrate concentrations of BCKA. To get meaningful data on the residual substrate degradation activities with intact fibroblasts of different phenotypes of MSUD physiologically low substrate concentrations are required in the assay. 10.1203/00006450-197509000-00005
Suppression of granulopoietic progenitor cell proliferation by metabolites of the branched-chain amino acids. Hutchinson R J,Bunnell K,Thoene J G The Journal of pediatrics The effects of branched-chain amino acid metabolites on granulocyte-macrophage progenitor cell proliferation in marrow culture are reported. Isovalerate and propionate profoundly suppress granulopoiesis at both 3.2 and 6.4 mM concentrations, whereas methylmalonate and other metabolites suppress to a lesser degree. The parent branched-chain amino acids leucine, isoleucine, and valine do not suppress in vitro granulopoiesis at similar concentrations. Because the concentrations of the organic acids tested fall within the pathophysiologic ranges observed in patients with isovaleric, propionic, and methylmalonic acidemias, we suggest that elevated in vivo levels of isovalerate, propionate, and to a lesser degree methylmalonate are responsible for the neutropenia observed in these disorders. 10.1016/s0022-3476(85)80466-2
N-(heterocyclic alkyl)pyrido[2,1-b]quinazoline-8-carboxamides as orally active antiallergy agents. Tilley J W,Levitan P,Lind J,Welton A F,Crowley H J,Tobias L D,O'Donnell M Journal of medicinal chemistry A series of N-(heterocyclic alkyl)pyrido[2,1-b]quinazoline-8-carboxamides were evaluated for their ability to antagonize slow-reacting substance of anaphylaxis (SRS-A) induced contractions of guinea pig ilea and to inhibit thromboxane synthase in vitro. The results indicated that those pyrido[2,1-b]quinazoline-8-carboxamides bearing a branched-chain alkyl moiety in the 2-position and a four to six atom linear chain between a 3- or 4-substituted pyridine or a 1-substituted imidazole ring and the carboxamide nitrogen atom showed the best combination of potencies in the two assays. Several of these compounds were found to be orally active inhibitors of LTE4-induced bronchoconstriction in the guinea pig and LTE4-induced skin wheal formation in the rat. One of the most potent analogues, 2-(1-methyl-ethyl)-N-(1H-imidazol-1-ylbutyl)-11-oxo-11H-pyrido [2,1-b]quinazoline-8-carboxamide (36), was selected for extensive pharmacological investigation. It was found that this compound was not a specific inhibitor of LTE4-induced symptomatology, but exhibited more general activity by inhibiting bronchospasm in guinea pigs induced by LTC4, LTD4, PAF, and histamine and skin wheal formation in rats and guinea pigs induced by LTC4, LTD4, and PAF. In addition, 36 was orally active in the passive cutaneous anaphylaxis assay, suggesting that it also exhibits mediator release inhibitory activity. On the basis of the overall pharmacological profile of 36 and its closely related analogues, it was concluded that these compounds may be useful for the treatment of asthma. 10.1021/jm00384a031
Physiology of Sporeforming Bacteria Associated with Insects II. Lipids of Vegetative Cells. Bulla L A,Bennett G A,Shotwell O L Journal of bacteriology Lipid composition was studied in two strains each of mid-log phase cells of Bacillus thuringiensis, B. larvae, B. popilliae, B. alvei, and B. lentimorbus. Total lipids varied from 2.5 to 3.5% of the cell dry weight of B. thuringiensis to 4.3 to 5.0% of B. popilliae. Phospholipids in the organisms examined ranged from 55 to 79% of total lipids; neutral lipids averaged from 13 to 45%. Common phospholipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, and lysophosphatidylethanolamine. 1,2-Diglycerides, methyl esters, free fatty acids, and hydrocarbons were found in all the organisms studied. Branched-chain fatty acids constituted more than 50% of the total fatty acids in B. thuringiensis, B. larvae, B. popilliae, and B. alvei, whereas, in B. lentimorbus, normal-chain acids constituted more than 50%. Anteiso-C(15) (12-methyltetradeconoate) was the most abundant acid (30 to 50%) in B. alvei, B. larvae, B. popilliae, and B. lentimorbus. In contrast, B. thuringiensis contained more iso-C(13) (7%), iso-C(15) (17%), normal-C(16) (24%), and iso-C(17) (18%) than anteiso-C(15) (6%). The distribution of individual fatty acids was similar in the phospholipids and neutral lipids of each organism. However, the total amount of iso, anteiso, and normal isomers differed. 10.1128/jb.104.3.1246-1253.1970
Effect of clofibrate feeding on palmitate and branched-chain 2-oxo acid oxidation in rat liver and muscle. Glatz J F,Wagenmakers A J,Veerkamp J H,van Moerkerk H T Biochemical pharmacology Oxidation rates of palmitate (total and antimycin-insensitive), pyruvate, leucine, 4-methyl-2-oxopentanoate and 3-methyl-2-oxobutanoate and activities of two mitochondrial marker enzymes (citrate synthase and cytochrome c oxidase) were assayed in liver and muscle homogenates of fed, clofibrate-treated and 18 hr-starved rats. Significant alterations in the clofibrate-treated and the starved rats were predominantly observed in the liver. Clofibrate feeding increased antimycin-insensitive (peroxisomal) and antimycin-sensitive (mitochondrial) palmitate oxidation and 4-methyl-2-oxopentanoate and pyruvate oxidation in liver. In muscle, only the activities of citrate synthase and cytochrome c oxidase were slightly decreased. Short starvation increased antimycin-sensitive palmitate and 4-methyl-2-oxopentanoate oxidation in liver. The rates of pyruvate and 3-methyl-2-oxobutanoate oxidation were decreased in muscle homogenates. Results suggest that myopathic phenomena observed after chronic clofibrate administration are not related to changes in the capacity of oxidative metabolism of muscle. 10.1016/0006-2952(83)90007-2
Long-chain diols: a new class of membrane lipids from a thermophilic bacterium. Pond J L,Langworthy T A,Holzer G Science (New York, N.Y.) Glycerol-derived membrane lipids are essentially absent in the thermophilic bacterium Thermomicrobium roseum. A series of straight chain and internally methyl-branched 1,2-diols of carbon numbers C(18) to C(23) were found to replace glycerolipids in this bacterium. Fatty acids were present but were ester-linked to the diols or amide-linked to polar heads groups and not to glycerol. This thermophile has evolved the integration of diols as a novel approach for the construction of its cytoplasmic membrane. 10.1126/science.231.4742.1134
Partial oxidation of leucine in skeletal muscle. Palmer T N,Gossain S,Sugden M C Biochemistry and molecular biology international 1. Leucine and its 2-oxo analogue, 4-methyl-2-oxopentanoate, increased the release of acetoacetate and 3-hydroxybutyrate from hemidiaphragms isolated from 40 h-starved rats. Glucose and lactate+pyruvate decreased basal and leucine-stimulated rates of ketone body production. 2. The production of acetoacetate + 3-hydroxybutyrate in response to addition of leucine was suppressed in hemidiaphragms from fed rats. 3. At 3 mM leucine, for each mumol of leucine oxidized in the branched-chain 2-oxo acid dehydrogenase reaction (measured as 14CO2 production from [1-14C]leucine), 0.84 mumol of acetoacetate + 3-hydroxybutyrate were produced. This stoichiometry may imply that acetoacetate derived from the partial oxidation of leucine is not further oxidized in situ. The physiological significance of these findings is discussed.
An efficient and general route to reduced polypropionates via Zr-catalyzed asymmetric CC bond formation. Negishi Ei-Ichi,Tan Ze,Liang Bo,Novak Tibor Proceedings of the National Academy of Sciences of the United States of America An efficient and general method for the synthesis of reduced polypropionates has been developed through the application of asymmetric carboalumination of alkenes catalyzed by dichlorobis(1-neomenthylindenyl)zirconium [(NMI)(2)ZrCl(2)]. In this investigation, attention has been focused on those reduced polypropionates that are alpha-monoheterofunctional and either omega-ethyl or omega-n-propyl. The reaction of 3-buten-1-ol with triethylaluminum (Et(3)Al) or tripropylaluminum ((n)Pr(3)Al) in the presence of (NMI)(2)ZrCl(2) and isobutylaluminoxane gave, after protonolysis, (R)-3-methyl-1-pentanol as well as (R)- and (S)-3-methyl-1-hexanols in 88-92% yield in 90-92% enantiomeric excess in one step. These 3-monomethyl-1-alkanols were then converted to two stereoisomers each of 2,4-dimethyl-1-hexanols and 2,4-dimethyl-1-heptanols via methylalumination catalyzed by (NMI)(2)ZrCl(2) and methylaluminoxane followed by oxidation with O(2). The four-step (or three-isolation-step) protocol provided syn-2,4-dimethyl-1-alkanols of >/=98% stereoisomeric purity in approximately 50% overall yields, whereas (2S,4R)-2,4-dimethyl-1-hexanol of comparable purity was obtained in 40% overall yield. Commercial availability of (S)-2-methyl-1-butanol as a relatively inexpensive material suggested its use in the synthesis of (2S,4S)- and (2R,4S)-2,4-dimethyl-1-hexanols via a three-step protocol consisting of (i) iodination, (ii) zincation followed by Pd-catalyzed vinylation, and (iii) Zr-catalyzed methylalumination followed by oxidation with O(2). This three-step protocol is iterative and applicable to the synthesis of reduced polypropionates containing three or more branching methyl groups, rendering this method for the synthesis of reduced polypropionates generally applicable. Its synthetic utility has been demonstrated by preparing the side chain of zaragozic acid A and the C11-C20 fragment of antibiotics TMC-151 A-F. 10.1073/pnas.0307514101
Distribution of per- and poly-fluoroalkyl substances and their precursors in human blood. Journal of hazardous materials Many studies have examined per- and poly-fluoroalkyl substances (PFASs) in human blood. However, the distribution of PFASs in human blood remains not well known, especially for perfluorooctane sulfonate (PFOS) precursors. In this study, human blood samples (n = 162) were collected from general Chinese population, and then the isomer-specific partitioning of PFASs between human plasma and red blood cells (RBCs) were investigated. Perfluorooctanoate (PFOA) and PFOS were consistently the predominant PFASs in both human plasma and RBCs. In human blood, among C-C perfluoroalkyl carboxylates (PFCAs), the calculated mean mass fraction in plasma (F) values increased from 0.76 to 0.82 with the increasing chain length. C-C PFCAs exhibited a trend of gradually decreasing mean F with chain length. Among PFAS precursors, 6:2 fluorotelomer phosphate diester had the highest mean F value (0.87 ± 0.11). Calculated F values of N-methyl perfluorooctanesulfonamide (N-MeFOSA) and N-ethyl perfluorooctanesulfonamide (N-EtFOSA) were 0.66 ± 0.13 and 0.70 ± 0.12, respectively. Individual branched isomers consistently had greater F values than their corresponding linear isomers for PFOA, PFHxS, and perfluoroctane sulfonamide. To our knowledge, this study first reports the distribution of N-MeFOSA and N-EtFOSA in human blood, contributing to the better understanding of the occurrence and fate of PFASs in humans. 10.1016/j.jhazmat.2022.129908
Relative importance of physiological precursors for ketogenesis in the nutritional homeostasis of the development of the embryonic chick. Bate A J,Dickson A J Biochimica et biophysica acta This paper investigates the relative importances of specific amino acids, and, in particular, branched chain amino acids and their keto derivatives as possible ketogenic precursors in suspensions of liver cells isolated from chick embryos. Addition of the branched chain keto acids stimulated ketogenesis. The order of potency was alpha-ketoisocaproic acid greater than alpha-ketoisovaleric acid greater than DL-alpha-keto-beta-methyl-n-valeric acid. The relative order of effectiveness for branched chain keto acids was maintained at all comparable concentrations, and in each case maximum rates were observed with concentrations of 1-2 mM. In contrast to the stimulation of ketogenesis by their keto derivatives, branched chain amino acids were ineffective as precursors for ketogenesis. Of the other amino acids (utilised at concentrations present in chick embryo plasma) only Tyr, Lys, Phe and Arg produced significant increases in ketone body formation above the endogenous rate. At these physiological concentrations, the effectiveness of the amino acids were in the order of Tyr greater than Lys = Phe greater than Arg. The interactions between three groups of ketogenic precursor (fatty acids, amino acids and keto amino acids, all at physiological concentrations), produced rates of ketogenesis that were purely additive. These results indicate that high concentrations of hydroxybutyrate and acetoacetate found in plasma of developing chick embryos may arise from hepatic metabolism of several distinct precursors. The relative importance of each category of precursor may vary with the precise developmental status of animals. 10.1016/0304-4165(87)90064-x
Assays for E1 and E2 components of the branched-chain keto acid dehydrogenase complex. Chuang D T Methods in enzymology 10.1016/s0076-6879(88)66021-6
Hepatic alpha-oxidation of phytanic acid. A revised pathway. Van Veldhoven P P,Mannaerts G P,Casteels M,Croes K Advances in experimental medicine and biology Synthetic 3-methyl-branched chain fatty acids were used to decipher the breakdown of phytanic acid. Based on results obtained in intact or permeabilized rat hepatocytes, rat liver homogenates or subcellular fractions, a revised alpha-oxidation pathway is proposed which appears to be functioning in man as well. In a first step, the 3-methyl-branched chain fatty acid is activated by an acyl-CoA synthetase. This reaction requires CoA, ATP and Mg2+. Subsequently, the acyl-CoA ester is hydroxylated at position 2 by a peroxisomal dioxygenase. This step is dependent on alpha-oxoglutarate, ascorbate (or glutathione), Fe2+ and O2. The 2-hydroxy-3-methylacyl-CoA intermediate is cleaved by a peroxisomal lyase to formyl-CoA and a 2-methyl-branched fatty aldehyde. Formyl-CoA is (partly enzymically) hydrolyzed to formate, which is then converted, most likely in the cytosol, to CO2. In the presence of NAD+, the aldehyde is dehydrogenated to a 2-methyl-branched fatty acid, presumably by a peroxisomal aldehyde dehydrogenase. This acid can--after activation--be degraded via a D-specific peroxisomal beta-oxidation system. 10.1007/0-306-46818-2_32
Mechanism and kinetics of low-temperature oxidation of a biodiesel surrogate: methyl propanoate radicals with oxygen molecule. Le Xuan T,Mai Tam V T,Ratkiewicz Artur,Huynh Lam K The journal of physical chemistry. A This paper presents a computational study on the low-temperature mechanism and kinetics of the reaction between molecular oxygen and alkyl radicals of methyl propanoate (MP), which plays an important role in low-temperature oxidation and/or autoignition processes of the title fuel. Their multiple reaction pathways either accelerate the oxidation process via chain branching or inhibit it by forming relatively stable products. The potential energy surfaces of the reactions between three primary MP radicals and molecular oxygen, namely, C(•)H2CH2COOCH3 + O2, CH3C(•)HCOOCH3 + O2, and CH3CH2COOC(•)H2 + O2, were constructed using the accurate composite CBS-QB3 method. Thermodynamic properties of all species as well as high-pressure rate constants of all reaction channels were derived with explicit corrections for tunneling and hindered internal rotations. Our calculation results are in good agreement with a limited number of scattered data in the literature. Furthermore, pressure- and temperature-dependent rate constants for all reaction channels on the multiwell-multichannel potential energy surfaces were computed with the quantum Rice-Ramsperger-Kassel (QRRK) and the modified strong collision (MSC) theories. This procedure resulted in a thermodynamically consistent detailed kinetic submechanism for low-temperature oxidation governed by the title process. A simplified mechanism, which consists of important reactions, is also suggested for low-temperature combustion at engine-like conditions. 10.1021/jp5128282
Nutritional control of branched chain alpha-ketoacid dehydrogenase in rat hepatocytes. Harris R A,Paxton R,Jenkins P Federation proceedings Branched chain alpha-ketoacid dehydrogenase (EC 1.2.4.4) complex, the rate-limiting enzyme of branched chain amino acid catabolism in most tissues, is subject to regulation by covalent modification, with phosphorylation inactivating and dephosphorylation activating the complex. The enzyme complex from liver of chow-fed rats is mainly in the active form but that from liver of rats fed a low-protein diet is mainly in the inactive form. Isolated hepatocytes were used to identify factors that affect interconversion of branched chain alpha-ketoacid dehydrogenase. The enzyme present in hepatocytes of rats fed a low-protein diet appears much more responsive to regulation by covalent modification than the branched chain alpha-ketoacid dehydrogenase present in hepatocytes of normal chow-fed rats. alpha-Chloroisocaproate, a specific inhibitor of the kinase responsible for phosphorylation and inactivation of the complex, greatly stimulates oxidation of alpha-keto[1-14C]isovalerate by hepatocytes prepared from rats fed a low-protein diet but not from normal chow-fed rats. Oxidizable substrates are also much more effective inhibitors of branched chain alpha-ketoacid oxidation with hepatocytes from rats fed a low-protein diet than from normal chow-fed rats. Activity measurements with cell-free extracts suggest that changes in flux through the dehydrogenase with intact hepatocytes prepared from rats fed a low-protein diet are explained in large part by changes in the proportion of the enzyme in the active, dephosphorylated form. Regulation of liver branched chain alpha-ketoacid dehydrogenase by covalent modification functions to conserve branched chain amino acids for protein synthesis during periods of restricted dietary protein intake.
A Highly Selective and Sensitive Chiral Derivatization Method for High- Performance Liquid Chromatographic Determination of the Stereoisomer Composition of Natural Products With Chiral Branched Alkyl Chains. Journal of chemical ecology In the study of chiral biologically active compounds such as pheromones, the analysis of the stereoisomer composition is essential to gain more insight into their stereochemical diversity, which affects the pheromone communication channels and therefore the diversification of species. This mini-review summarizes the development of fluorescence derivatization reagents for high-performance liquid chromatographic (HPLC) determination of the absolute configuration and stereoisomer composition of natural products with a chiral branched alkyl chain. The diastereomeric separation of anteiso fatty acids bearing a branched methyl group up to the C-26 position was achieved by reversed-phase HPLC under very low column temperature conditions using (1S,2S)-2-(2,3-anthracenedicarboximido)cyclohexanol as a derivatization reagent, enabling fluorescent detection of these compounds at femtomole levels. This method was also applicable to chiral alcohols and amines with chiral branched methyl groups using similar reagents containing a carboxyl group. These reagents were successfully applied to determine the absolute configurations and stereoisomer composition of the chiral alkyl chain of natural compounds including some insect pheromones, miyakosyne A, and plakoside A. The combination of these reagents and two-dimensional HPLC constitutes a very powerful tool for the analysis of the stereoisomers of natural crude samples. Furthermore, the analysis of some natural bioactive substances using this method demonstrated that natural substances are not always optically pure, consisting instead of stereoisomer mixtures exhibiting stronger activity than optically pure enantiomers. These results cast doubts on the concept of biological homochirality and demonstrate that natural pheromones do not always show the highest activity among all stereoisomers. 10.1007/s10886-021-01345-z
Generation of volatile fatty acids by axillary bacteria. James A G,Hyliands D,Johnston H International journal of cosmetic science It is generally accepted that short-chain (C(2)-C(5)) volatile fatty acids (VFAs) are among the causal molecules of axillary malodour. It is also widely acknowledged that malodour generation is attributable to the biotransformation of odourless natural secretions, into volatile odorous products, by axillary bacteria. However, little information is available on the biochemical origins of VFAs on axillary skin. In these studies, assay systems were developed to investigate the generation of VFAs from substrates readily available to the bacteria resident on axillary skin. Propionibacteria and staphylococci were shown to ferment glycerol and lactic acid to the short-chain (C(2)-C(3)) VFAs, acetic and propionic acid. Furthermore, staphylococci are capable of converting branched aliphatic amino acids, such as leucine, to highly odorous short-chain (C(4)-C(5)) methyl-branched VFAs, such as isovaleric acid, which are traditionally associated with the acidic note of axillary malodour. However, in vitro kinetic data indicates that these pathways contribute less to axillary VFA levels, than fatty acid biotransformations by a recently defined sub-group of the Corynebacterium genus, corynebacteria (A). The results of these studies provide new understanding on the biochemical origins of VFA-based axillary malodour which, in turn, should lead to the development of novel deodorant systems. 10.1111/j.1467-2494.2004.00214.x
Further stereochemical studies of phthiocerol and phenol phthiocerol in mycobacteria. Daffé M Research in microbiology Mycobacterium tuberculosis, M. marinum and some other pathogenic species elaborate waxes A, based on a long-chain beta-diol (phthiocerol and companion compounds) and polymethyl-branched fatty acids. The stereochemical studies conducted on waxes A showed that those of M. tuberculosis, M. leprae and M. kansasii differ from waxes A isolated from M. marinum and M. ulcerans by the absolute configuration of the methyl-branched chiral centres occurring in both the long-chain beta-diols and the fatty acyls. Furthermore, the two mycobacterial groups also differ in the stereochemistry of the beta-diol chiral centres.
Ligand-induced conformational changes and a reaction intermediate in branched-chain 2-oxo acid dehydrogenase (E1) from Thermus thermophilus HB8, as revealed by X-ray crystallography. Nakai Tadashi,Nakagawa Noriko,Maoka Nobuko,Masui Ryoji,Kuramitsu Seiki,Kamiya Nobuo Journal of molecular biology The alpha(2)beta(2) tetrameric E1 component of the branched-chain 2-oxo acid (BCOA) dehydrogenase multienzyme complex is a thiamin diphosphate (ThDP)-dependent enzyme. E1 catalyzes the decarboxylation of a BCOA concomitant with the formation of the alpha-carbanion/enamine intermediate, 2-(1-hydroxyalkyl)-ThDP, followed by transfer of the 1-hydroxyalkyl group to the distal sulfur atom on the lipoamide of the E2 component. In order to elucidate the catalytic mechanism of E1, the alpha- and beta-subunits of E1 from Thermus thermophilus HB8 have been co-expressed in Escherichia coli, purified and crystallized as a stable complex, and the following crystal structures have been analyzed: the apoenzyme (E1(apo)), the holoenzyme (E1(holo)), E1(holo) in complex with the substrate analogue 4-methylpentanoate (MPA) as an ES complex model, and E1(holo) in complex with 4-methyl-2-oxopentanoate (MOPA) as the alpha-carbanion/enamine intermediate (E1(ceim)). Binding of cofactors to E1(apo) induces a disorder-order transition in two loops adjacent to the active site. Furthermore, upon binding of MPA to E1(holo), the loop comprised of Gly121beta-Gln131beta moves close to the active site and interacts with MPA. The carboxylate group of MPA is recognized mainly by Tyr86beta and N4' of ThDP. The hydrophobic moiety of MPA is recognized by Phe66alpha, Tyr95alpha, Met128alpha and His131alpha. As an intermediate, MOPA is decarboxylated and covalently linked to ThDP, and the conformation of the protein loop is almost the same as in the substrate-free (holoenzyme) form. These results suggest that E1 undergoes an open-closed conformational change upon formation of the ES complex with a BCOA, and the mobile region participates in the recognition of the carboxylate group of the BCOA. ES complex models of E1(holo).MOPA and of E1(ceim).lipoamide built from the above structures suggest that His273alpha and His129beta' are potential proton donors to the carbonyl group of a BCOA and to the proximal sulfur atom on the lipoamide, respectively. 10.1016/j.jmb.2004.02.011
Specificity of the effects of leucine and its metabolites on protein degradation in skeletal muscle. Mitch W E,Clark A S The Biochemical journal The effects of leucine, its metabolites, and the 2-oxo acids of valine and isoleucine on protein synthesis and degradation in incubated limb muscles of immature and adult rats were tested. Leucine stimulated protein synthesis but did not reduce proteolysis when leucine transamination was inhibited. 4-Methyl-2-oxopentanoate at concentrations as low as 0.25 mM inhibited protein degradation but did not change protein synthesis. The 2-oxo acids of valine and isoleucine did not change protein synthesis or degradation even at concentrations as high as 5 mM. 3-Methylvalerate, the irreversibly decarboxylated product of 4-methyl-2-oxopentanoate, decreased protein degradation at concentrations greater than or equal to 1 mM. This was not due to inhibition of 4-methyl-2-oxopentanoate catabolism, because 0.5 mM-3-methylvalerate did not suppress proteolysis, even though it inhibited leucine decarboxylation by 30%; higher concentrations of 3-methylvalerate decreased proteolysis progressively without inhibiting leucine decarboxylation further. During incubation with [1-14C]- and [U-14C]-leucine, it was found that products of leucine catabolism formed subsequent to the decarboxylation of 4-methyl-2-oxopentanoate accumulated intracellularly. This pattern was not seen during incubation with radiolabelled valine. Thus, the effect of leucine on muscle proteolysis requires transamination to 4-methyl-2-oxopentanoate. The inhibition of muscle protein degradation by leucine is most sensitive to, but not specific for, its 2-oxo acid, 4-methyl-2-oxopentanoate. 10.1042/bj2220579
Characterization of Four Alkyl-branched Fatty Acids as Methyl, Ethyl, Propyl, and Butyl Esters Using Gas Chromatography-Quadrupole Time of Flight Mass Spectrometry. Analytical sciences : the international journal of the Japan Society for Analytical Chemistry Branched fatty chain fatty acids (BCFAs) are associated with the "mutton flavor" found with the aroma resulting from cooked older sheep meat with three BCFAs, 4-methyloctanoic (MOA), 4-ethyloctanoic (EOA) and 4-methylnonanoic (MNA) acids as the main compounds responsible for "mutton flavor". Usually, BCFA analysis is done by gas chromatography (GC) with the use of quadrupole mass spectrometry (qMS) becoming predominant. 2-Butyloctanoic acid (2BO) has been used in this facility using as an internal standard to determine BCFA content in sheep fat. In this present work, GC-qMS, along with GC-quadrupole-time of flight MS (GC-QTOF-MS), have been deployed to characterize alkyl esters (as methyl, ethyl, propyl, and butyl) for MOA, EOA, MNA, and 2BO. This work presents, for the first time, the mass spectral characterization of 2BO for these alkyl esters using GC-qMS and GC-QTOF-MS. 10.2116/analsci.19P349
GC-MS-Based Analysis of Methanol: Chloroform-extracted Fatty Acids from Plant Tissues. Patel Manish Kumar,Das Shubhashis,Thakur Jitendra Kumar Bio-protocol Fatty acids (FAs) are carboxylic acids with long aliphatic chains that may be straight, branched and saturated or unsaturated. Most of the naturally occurring plant FAs contains an even number of carbon (C4-C24). FAs are used in food and pharmacological industries due to their nutritional importance. In addition, FAs are considered as a promising alternative for the production of biodiesel from terrestrial plant biomass. To establish commercial applications, more reliable analytical methods are needed for the identification, quantification, and composition determination of FAs. Here, we describe a relatively rapid and sensitive method for the extraction, identification, and quantification of FAs from a small quantity of plant tissue. The method includes steps of lipid extraction, conversion of lipid to fatty acid methyl esters (FAMEs) by transmethylation, identification and quantification of FAMEs using gas chromatography-mass spectrometry (GC-MS). In this protocol, an internal standard is added prior to GC-MS analysis. The amount of each FA is calculated from its peak area relative to the peak area of the internal standard. 10.21769/BioProtoc.3014
Synthesis and hypoglycemic activity of N-alkylated hydrazonopropionic acids. Wolff H P,Kühnle H F Journal of medicinal chemistry A series of N-alkylated 2-hydrazonopropionic acids have been synthesized and evaluated for their hypoglycemic activity. Most of the compounds exhibit a remarkable blood glucose lowering activity in fasted guinea pigs. Some of the structural variables studied were the effects of branching, unsaturation, or substitution on the alkyl side chain and the effect of nuclear substitution on the aralkyl analogues. From these compounds, 2-[[(E)-2-methyl-3-phenyl-2-propenyl]hydrazono]propionic acid (BM 42.304; 42) was selected for further investigation. 10.1021/jm00148a011
Carbon dioxide fixation in green sulphur bacteria. Sirevåg R,Ormerod J G The Biochemical journal 1. About one-third of the CO(2) fixed during photosynthesis by washed suspensions of Chlorobium thiosulfatophilum strain 8346 gave rise to alpha-oxoglutarate and branched-chain oxo acids, mainly beta-methyl-alpha-oxovalerate. Another one-third to one-half gave rise to a polyglucose. 2. The fixation of CO(2) was inhibited by fluoroacetate, increasing concentrations up to 1mm stimulating the accumulation of alpha-oxoglutarate and causing a decrease in the formation of the branched-chain oxo acids and polyglucose. 3. Acetate was converted into the same products as was CO(2). 4. Fluoroacetate (1mm) had a negligible effect on the formation of polyglucose from acetate and caused a slight inhibition of the formation of the branched-chain oxo acids and increased accumulation of alpha-oxoglutarate. 5. Iodoacetate (1mm) strongly inhibited polyglucose formation from acetate and caused accumulation of pyruvate. The formation of the branched-chain oxo acids from acetate was only slightly affected by this inhibitor. 6. Pyruvate can be metabolized by this organism in the presence of a suitable electron donor whether CO(2) is present or not. In the absence of CO(2) pyruvate is converted into polyglucose. 7. The accumulation of oxo acids during CO(2) fixation is completely inhibited by NH(4) (+) ions. The formation of the branched-chain oxo acids is considerably decreased by the presence of isoleucine, leucine or valine, or a mixture of these. 8. CO(2) fixation in two other strains of Chlorobium appears to exhibit a similar pattern to that in C. thiosulfatophilum strain 8346. 9. It is concluded that in washed suspensions, CO(2) is fixed mainly by a mechanism involving the reductive carboxylic acid cycle. Acetate, the product of the cycle, is converted into polyglucose via pyruvate synthase and a reversal of glycolysis or into branched-chain oxo acids by an unknown mechanism. 10.1042/bj1200399
Purification of a branched-chain keto acid dehydrogenase from Pseudomonas putida. Sokatch J R,McCully V,Roberts C M Journal of bacteriology We purified branched-chain keto acid dehydrogenase to a specific activity of 10 mumol/min per mg of protein from Pseudomonas putida grown on valine. The purified enzyme was active with 2-ketoisovalerate, 2-ketoisocaproate, and 2-keto-3-methylvalerate in a ratio of 1.0:0.8:0.7 but showed no activity with either pyruvate or 2-ketoglutarate. There were four polypeptides in the purified enzyme (molecular weights, 49,000, 46,000, 39,000, and 37,000). The purified enzyme was deficient in the specific lipoamide dehydrogenase produced during growth on valine (molecular weight, 49,000). Branched-chain keto acid dehydrogenase required L-valine, oxidized nicotinamide adenine dinucleotide, coenzyme A, thiamine pyrophosphate, and magnesium chloride. A partially purified preparation catalyzed the oxidation of 2-keto-[1-14C]isovalerate to [14C]carbon dioxide, isobutyryl-coenzyme A, and reduced nicotinamide adenine dinucleotide in equimolar amounts. Both the Km and the Vmax for 2-ketoisovalerate were affected by the addition of L-valine to the assay mixture. However, only the Vmax values for oxidized nicotinamide adenine dinucleotide and coenzyme A were affected when L-valine was present. This suggested that valine acted by affecting the binding of branched-chain keto acids to subunit E1 of the complex. 10.1128/jb.148.2.647-652.1981
Enzymes involved in branched-chain amino acid metabolism in humans. Adeva-Andany María M,López-Maside Laura,Donapetry-García Cristóbal,Fernández-Fernández Carlos,Sixto-Leal Cristina Amino acids Branched-chain amino acids (leucine, isoleucine and valine) are structurally related to branched-chain fatty acids. Leucine is 2-amino-4-methyl-pentanoic acid, isoleucine is 2-amino-3-methyl-pentanoic acid, and valine is 2-amino-3-methyl-butanoic acid. Similar to fatty acid oxidation, leucine and isoleucine produce acetyl-coA. Additionally, leucine generates acetoacetate and isoleucine yields propionyl-coA. Valine oxidation produces propionyl-coA, which is converted into methylmalonyl-coA and succinyl-coA. Branched-chain aminotransferase catalyzes the first reaction in the catabolic pathway of branched-chain amino acids, a reversible transamination that converts branched-chain amino acids into branched-chain ketoacids. Simultaneously, glutamate is converted in 2-ketoglutarate. The branched-chain ketoacid dehydrogenase complex catalyzes the irreversible oxidative decarboxylation of branched-chain ketoacids to produce branched-chain acyl-coA intermediates, which then follow separate catabolic pathways. Human tissue distribution and function of most of the enzymes involved in branched-chain amino acid catabolism is unknown. Congenital deficiencies of the enzymes involved in branched-chain amino acid metabolism are generally rare disorders. Some of them are associated with reduced pyruvate dehydrogenase complex activity and respiratory chain dysfunction that may contribute to their clinical phenotype. The biochemical phenotype is characterized by accumulation of the substrate to the deficient enzyme and its carnitine and/or glycine derivatives. It was established at the beginning of the twentieth century that the plasma level of the branched-chain amino acids is increased in conditions associated with insulin resistance such as obesity and diabetes mellitus. However, the potential clinical relevance of this elevation is uncertain. 10.1007/s00726-017-2412-7
Erratum to: Low-energy tandem mass spectrometry of the molecular ion derived from fatty acid methyl esters: A novel method for analysis of branched-chain fatty acids. Zirrolli J A,Murphy R C Journal of the American Society for Mass Spectrometry 10.1016/1044-0305(93)80046-2
A practical synthesis of long-chain iso-fatty acids (iso-C12-C19) and related natural products. Richardson Mark B,Williams Spencer J Beilstein journal of organic chemistry A gram-scale synthesis of terminally-branched iso-fatty acids (iso-C12-C19) was developed commencing with methyl undec-10-enoate (methyl undecylenate) (for iso-C12-C14) or the C15 and C16 lactones pentadecanolide (for iso-C15-C17) and hexadecanolide (for iso-C18-C19). Central to the approaches outlined is the two-step construction of the terminal isopropyl group through addition of methylmagnesium bromide to the ester/lactones and selective reduction of the resulting tertiary alcohols. Thus, the C12, C17 and C18 iso-fatty acids were obtained in three steps from commercially-available starting materials, and the remaining C13-C16 and C19 iso-fatty acids were prepared by homologation or recursive dehomologations of these fatty acids or through intercepting appropriate intermediates. Highlighting the synthetic potential of the iso-fatty acids and various intermediates prepared herein, we describe the synthesis of the natural products (S)-2,15-dimethylpalmitic acid, (S)-2-hydroxy-15-methylpalmitic acid, and 2-oxo-14-methylpentadecane. 10.3762/bjoc.9.210
Crystal structure of 2-oxoisovalerate and dehydrogenase and the architecture of 2-oxo acid dehydrogenase multienzyme complexes. Aevarsson A,Seger K,Turley S,Sokatch J R,Hol W G Nature structural biology The family of giant multienzyme complexes metabolizing pyruvate, 2-oxoglutarate, branched-chain 2-oxo acids or acetoin contains several of the largest and most sophisticated protein assemblies known, with molecular masses between 4 and 10 million Da. The principal enzyme components, E1, E2 and E3, are present in numerous copies and utilize multiple cofactors to catalyze a directed sequence of reactions via substrate channeling. The crystal structure of a heterotetrameric (alpha2beta2) E1, 2-oxoisovalerate dehydrogenase from Pseudomonas putida, reveals a tightly packed arrangement of the four subunits with the beta2-dimer held between the jaws of a 'vise' formed by the alpha2-dimer. A long hydrophobic channel, suitable to accommodate the E2 lipoyl-lysine arm, leads to the active site, which contains the cofactor thiamin diphosphate (ThDP) and an inhibitor-derived covalent modification of a histidine side chain. The E1 structure, together with previous structural information on E2 and E3, completes the picture of the shared architectural features of these enormous macromolecular assemblies. 10.1038/11563
The phospholipid fatty acids of the marine spongeXestospongia muta. Carballeira N M,Maldonado L Lipids The rare phospholipid fatty acids 3,7,11-trimethyldodecanoic (1), 5,9-hexadecadienoic (2) and 12-methyl-hexadecanoic (3) were identified in the marine spongeXestospongia muta. Branched fatty acids inX. muta accounted for 35% of the total fatty acid mixture. It was observed that the occurrence of the 5,9-hexadecadienoic acid (2) coincides with the complete absence of the very long chain fatty acid 5,9-hexacosadienoic. The acid 5,9,19-octacosatrienoic seems to be found in mostXestospongia species. 10.1007/BF02535668
Dissociation of branched-chain alpha-keto acid dehydrogenase kinase (BDK) from branched-chain alpha-keto acid dehydrogenase complex (BCKDC) by BDK inhibitors. Murakami Taro,Matsuo Masayuki,Shimizu Ayako,Shimomura Yoshiharu Journal of nutritional science and vitaminology Branched-chain alpha-keto acid dehydrogenase kinase (BDK) phosphorylates and inactivates the branched-chain alpha-keto acid dehydrogenase complex (BCKDC), which is the rate-limiting enzyme in the branched-chain amino acid catabolism. BDK has been believed to be bound to the BCKDC. However, recent our studies demonstrated that protein-protein interaction between BDK and BCKDC is one of the factors to regulate BDK activity. Furthermore, only the bound form of BDK appears to have its activity. In the present study, we examined effects of BDK inhibitors on the amount of BDK bound to the BCKDC using rat liver extracts. The bound form of BDK in the extracts of liver from low protein diet-fed rats was measured by an immunoprecipitation pull down assay with or without BDK inhibitors. Among the BDK inhibitors. alpha-ketoisocaproate, alpha-chloroisocaproate, and a-ketoisovalerate released the BDK from the complex. Furthermore, the releasing effect of these inhibitors on the BDK appeared to depend on their inhibition constants. On the other hand, clofibric acid and thiamine pyrophosphate had no effect on the protein-protein interaction between two enzymes. These results suggest that the dissociation of the BDK from the BCKDC is one of the mechanisms responsible for the action of some inhibitors to BDK.
Analogues of thiolactomycin: potential drugs with enhanced anti-mycobacterial activity. Douglas James D,Senior Suzanne J,Morehouse Caroline,Phetsukiri Benjawan,Campbell Ian B,Besra Gurdyal S,Minnikin David E Microbiology (Reading, England) Analogues of the antibiotic thiolactomycin (TLM) have been synthesized and have been shown to have enhanced activity against whole cells of Mycobacterium tuberculosis H37Rv and against mycolic acid biosynthesis in cell extracts of Mycobacterium smegmatis. TLM has a methyl-branched butadienyl side chain attached at position 5 on a 'thiolactone' ring, namely 4-hydroxy-3,5-dimethyl-5H-thiophen-2-one. Various combinations of strong bases were explored to create a reactive anion at position 5 on the thiolactone ring which could react with halides to produce 5-substituted derivatives; the best reagent was two equivalents of lithium-bis-(trimethylsilyl)amide in tetrahydrofuran. The analogue with a 5-tetrahydrogeranyl substituent showed the best biological activity with an MIC(90) for M. tuberculosis of 29 micro M and 92% mycolate inhibition in extracts of M. smegmatis, as compared to 125 micro M and 54%, respectively, for TLM; other related C(10) and C(15) isoprenoid derivatives had similar biological activity. These isoprenoid-based derivatives did not inhibit type II fatty acid synthase from M. smegmatis, but compounds with iso-butyl and iso-butenyl side chains did show some inhibitory activity against this enzyme. These short-chain derivatives did not inhibit mycolate synthesis or have significant antibiotic activity. Treatment of the thiolactone with a weaker base, sodium hydride in tetrahydrofuran, gave 3-alkyl-3,5-dimethyl-thiophene-2,4-dione analogues, which had no effect on fatty acid or mycolate synthesis. However, the geranyl derivative had an MIC(99) of 60 micro M for M. tuberculosis, one quarter that (240 micro M) of TLM, demonstrating its excellent antibiotic potential against an unknown cellular target. 10.1099/00221287-148-10-3101
Open Culture Ethanol-Based Chain Elongation to Form Medium Chain Branched Carboxylates and Alcohols. de Leeuw Kasper D,Ahrens Theresa,Buisman Cees J N,Strik David P B T B Frontiers in bioengineering and biotechnology Chain elongation fermentation allows for the synthesis of biobased chemicals from complex organic residue streams. To expand the product spectrum of chain elongation technology and its application range we investigated 1) how to increase selectivity towards branched chain elongation and 2) whether alternative branched carboxylates such as branched valerates can be used as electron acceptors. Elongation of isobutyrate elongation towards 4-methyl-pentanoate was achieved with a selectivity of 27% (of total products, based on carbon atoms) in a continuous system that operated under CO and acetate limited conditions. Increasing the CO load led to more acetate formation that increased overall chain elongation rate but decreased the selectivity of branched chain elongation. A part of this acetate formation was related to direct ethanol oxidation that seemed to be thermodynamically coupled to hydrogenotrophic carboxylate reduction to corresponding alcohols. Several alcohols including isobutanol and n-hexanol were formed. The microbiome from the continuous reactor was also able to form small amounts of 5-methyl-hexanoate likely from 3-methyl-butanoate and ethanol as substrate in batch experiments. The highest achieved concentration of isoheptanoate was 6.4 ± 0.9 mM Carbon, or 118 ± 17 mg/L, which contributed for 7% to the total amount of products (based on carbon atoms). The formation of isoheptanoate was dependent on the isoform of branched valerate. With 3-methyl-butanoate as substrate 5-methylhexanoate was formed, whereas a racemic mixture of L/D 2-methyl-butanoate did not lead to an elongated product. When isobutyrate and isovalerate were added simultaneously as substrates there was a large preference for elongation of isobutyrate over isovalerate. Overall, this work showed that chain elongation microbiomes can be further adapted with supplement of branched-electron acceptors towards the formation of iso-caproate and iso-heptanoate as well as that longer chain alcohol formation can be stimulated. 10.3389/fbioe.2021.697439
The Effects of Carbon Source and Growth Temperature on the Fatty Acid Profiles of . Frontiers in molecular biosciences The aerobic, thermophilic , has been proposed as an organism to be used for the efficient conversion of plant biomass to fatty acid-derived precursors of biofuels or biorenewable chemicals. Despite the potential of to catabolize plant biomass, there is remarkably little data available concerning the natural ability of this organism to produce fatty acids. Therefore, we determined the fatty acids that produces when it is grown on different carbon sources (i.e., glucose, cellobiose, cellulose and avicel) and at two different growth temperatures, namely at the optimal growth temperature of 50°C and at a suboptimal temperature of 37°C. These analyses establish that produces a combination of linear and branched chain fatty acids (BCFAs), including -, -, and 10-methyl BCFAs that range between 14- and 18-carbons in length. Although different carbon sources and growth temperatures both quantitatively and qualitatively affect the fatty acid profiles produced by , growth temperature is the greater modifier of these traits. Additionally, genome scanning enabled the identification of many of the fatty acid biosynthetic genes encoded by . 10.3389/fmolb.2022.896226
The design and biological properties of iodine-123 labelled beta-methyl-branched fatty acids. Knapp F F,Goodman M M European heart journal 10.1093/eurheartj/6.suppl_b.71
Dietary fatty acid metabolism: New insights into the similarities of lipid metabolism in humans and hamsters. Food chemistry. Molecular sciences Hamsters have been long accepted as animal models to study the lipid metabolism in humans. However, very few scientific works described in detail the fatty acid (FA) composition of plasma and erythrocytes in hamsters in relation to their dietary intake, and none work was found comparing them with that described in humans. Therefore, a study was carried out to compare the effect of ingesting olive oil or dairy fat, as part of an equilibrated diet in healthy subjects, on plasma and erythrocytes FA composition. More than 40 FA were detected in samples of both species. It was demonstrated that plasma total FA (TFA) concentration and FA profiles are similar in humans and hamsters. In both species linoleic, oleic and palmitic acids are the main FA and accounted for the 70% of TFA. Differences found between species can be explained by differences in the dietary intake and differences in the proportion of triglycerides, cholesteryl esters and phospholipid fractions in plasma of both species. Changes in dietary FA intake causes similar changes in FA concentration in the plasma of both species and can be explained by the same metabolic processes. The erythrocyte FA profile differs more between the two species. Moreover, unlike humans, the FA profile of hamster erythrocytes is more sensitive to changes in dietary FA than that of plasma. 10.1016/j.fochms.2021.100060
Conformationally constrained analogues of diacylglycerol (DAG). 16. How much structural complexity is necessary for recognition and high binding affinity to protein kinase C? Nacro K,Bienfait B,Lee J,Han K C,Kang J H,Benzaria S,Lewin N E,Bhattacharyya D K,Blumberg P M,Marquez V E Journal of medicinal chemistry The design of potent protein kinase C (PK-C) ligands with low nanomolar binding affinities was accomplished by the combined use of pharmacophore- and receptor-guided approaches based on the structure of the physiological enzyme activator, diacylglycerol (DAG). Earlier use of the former approach, which was based on the structural equivalence of DAG and phorbol ester pharmacophores, identified a fixed template for the construction of a semirigid "recognition domain" that contained the three principal pharmacophores of DAG constrained into a lactone ring (DAG-lactones). In the present work, the pharmacophore-guided approach was refined to a higher level based on the X-ray structure of the C1b domain of PK-Cdelta complexed with phorbol-13-O-acetate. A systematic search that involved modifying the DAG-lactone template with a combination of linear or branched acyl and alpha-alkylidene chains, which functioned as variable hydrophobic "affinity domains", helped identify compounds that optimized hydrophobic contacts with a group of conserved hydrophobic amino acids located on the top half of the C1 domain where the phorbol binds. The hydrophilic/hydrophobic balance of the molecules was estimated by the octanol/water partition coefficients (log P) calculated according to a fragment-based approach. The presence of branched alpha-alkylidene or acyl chains was of critical importance to reach low nanomolar binding affinities for PK-C. These branched chains appear to facilitate important van der Waals contacts with hydrophobic segments of the protein and help promote the activation of PK-C through critical membrane interactions. Molecular modeling of these DAG-lactones into an empty C1b domain using the program AutoDock 2.4 suggests the existence of competing binding modes (sn-1 and sn-2) depending on which carbonyl is directly involved in binding to the protein. Inhibition of epidermal growth factor (EGF) binding, an indirect PK-C mediated response, was realized with some DAG-lactones at a dose 10-fold higher than with the standard phorbol-12, 13-dibutyrate (PDBU). Through the National Cancer Institute (NCI) 60-cell line in vitro screen, DAG-lactone 31 was identified as a very selective and potent antitumor agent. The NCI's computerized, pattern-recognition program COMPARE, which analyzes the degree of similarity of mean-graph profiles produced by the screen, corroborated our principles of drug design by matching the profile of compound 31 with that of the non-tumor-promoting antitumor phorbol ester, prostratin. The structural simplicity and the degree of potency achieved with some of the DAG-lactones described here should dispel the myth that chemical complexity and pharmacological activity go hand in hand. Even as a racemate, DAG-lactone 31 showed low namomolar binding affinity for PK-C and displayed selective antitumor activity at equivalent nanomolar levels. Our present approach should facilitate the generation of multiple libraries of structurally similar DAG-lactones to help exploit molecular diversity for PK-C and other high-affinity receptors for DAG and the phorbol esters. The success of this work suggests that substantially simpler, high-affinity structures could be identified to function as surrogates of other complex natural products. 10.1021/jm9904607
Metabolic effects of inhibitors of two enzymes of the branched-chain amino acid pathway in Salmonella typhimurium. Epelbaum S,Chipman D M,Barak Z Journal of bacteriology The metabolic effects of inhibitors of two enzymes in the pathway for biosynthesis of branched-chain amino acids were examined in Salmonella typhimurium mutant strain TV105, expressing a single isozyme of acetohydroxy acid synthase (AHAS), AHAS isozyme II. One inhibitor was the sulfonylurea herbicide sulfometuron methyl (SMM), which inhibits this isozyme and AHAS of other organisms, and the other was N-isopropyl oxalylhydroxamate (IpOHA), which inhibits ketol-acid reductoisomerase (KARI). The effects of the inhibitors on growth, levels of several enzymes of the pathway, and levels of intermediates of the pathway were measured. The intracellular concentration of the AHAS substrate 2-ketobutyrate increased on addition of SMM, but a lack of correlation between increased ketobutyrate and growth inhibition suggests that the former is not the immediate cause of the latter. The levels of the keto acid precursor of valine, but not of the precursor of isoleucine, were drastically decreased by SMM, and valine, but not isoleucine, partially overcame SMM inhibition. This apparent stronger effect of SMM on the flux into the valine arm, as opposed to the isoleucine arm, of the branched-chain amino acid pathway is explained by the kinetics of the AHAS reaction, as well as by the different roles of pyruvate, ketobutyrate, and the valine precursor in metabolism. The organization of the pathway thus potentiates the inhibitory effect of SMM. IpOHA has strong initial effects at lower concentrations than does SMM and leads to increases both in the acetohydroxy acid substrates of KARI and, surprisingly, in ketobutyrate. Valine completely protected strain TV105 from IpOHA at the MIC. A number of explanations for this effect can be ruled out, so that some unknown arrangement of the enzymes involved must be suggested. IpOHA led to initial cessation of growth, with partial recovery after a time whose duration increased with the inhibitor concentration. The recovery is apparently due to induction of new KARI synthesis, as well as disappearance of IpOHA from the medium. 10.1128/jb.178.4.1187-1196.1996
Dietary L-carnitine suppresses mitochondrial branched-chain keto acid dehydrogenase activity and enhances protein accretion and carcass characteristics of swine. Owen K Q,Jit H,Maxwell C V,Nelssen J L,Goodband R D,Tokach M D,Tremblay G C,Koo S I Journal of animal science A trial was conducted to biochemically explain the decreased lipid deposition and increased protein accretion observed in pigs fed carnitine. Our hypothesis was that an increase in the ratio of acetyl CoA:CoA-SH produced by stimulation of fatty acid oxidation by supplemental L-carnitine may decrease branched-chain alpha-keto acid dehydrogenase activity and increase pyruvate carboxylase activity. Such changes could reduce oxidative loss of branched-chain amino acids and provide more carbons for amino acid biosynthesis. Yorkshire gilts (n = 36; 12 per treatment) were fed a control diet or diets containing either 50 or 125 ppm of added L-carnitine during growth from 56 to 120 kg. After slaughter, the semitendinosus muscle and liver were collected for isolation of mitochondria and hepatocytes. Increasing dietary L-carnitine did not influence growth performance (P > 0.10) but linearly decreased (P < 0.05) 10th rib backfat thickness and increased (linear, P < 0.05) percentages of lean and muscle. The rates of [1-(14)G]palmitate oxidation in isolated hepatocytes and isolated mitochondria, and incorporation of [35S]methionine into the acid insoluble fraction of isolated hepatocytes were increased (linear, P < 0.01) in pigs fed L-carnitine. Flux through branched-chain alpha-keto acid dehydrogenase linearly decreased (P < 0.01) in isolated liver and muscle mitochondria with increasing dietary carnitine. Flux through pyruvate carboxylase was increased (linear, P < 0.01) in isolated mitochondria from liver of pigs fed carnitine, and assays with particle-free extracts indicated that the amount of mitochondrial pyruvate carboxylase was tripled by feeding carnitine (linear, P < 0.01). The association of increased protein accretion and reduced backfat thickness with greater rates of palmitate oxidation, more rapid flux through pyruvate carboxylase, and reduced flux through branched-chain alpha-keto acid dehydrogenase suggests pigs fed carnitine are more able to use fat for energy, divert carbon toward synthesis of amino acids, and spare branched-chain amino acids for protein synthesis. 10.2527/2001.79123104x
Distribution of phthiocerol diester, phenolic mycosides and related compounds in mycobacteria. Daffé M,Laneelle M A Journal of general microbiology Among 28 mycobacterial species studied, only Mycobacterium tuberculosis, M. bovis, M. africanum, M. marinum, M. kansasii, M. gastri and M. ulcerans produced waxes yielding long-chain beta-diol components (called phthiocerol and companions) and polymethyl-branched fatty acids on saponification. The same mycobacterial species also produced diesters of phenol phthiocerol and companions. Fatty acids esterifying these fatty alcohols in M. marinum and M. ulcerans were found to belong to the phthioceranic series (dextrorotatory fatty acids), in contrast to those of the other species (laevorotatory fatty acids called mycocerosic acids), both groups having the same chain length and methyl-branched positions. M. kansasii and M. gastri contained the same waxes with identical structures, as did M. tuberculosis, M. bovis and M. africanum. Neither the type strain of M. tuberculosis, nor that of M. bovis or M. marinum accumulated the strain-specific phenolic glycolipids. 10.1099/00221287-134-7-2049
Lipoic acid metabolism in Trypanosoma cruzi as putative target for chemotherapy. Vacchina Paola,Lambruschi Daniel A,Uttaro Antonio D Experimental parasitology Lipoic acid (LA) is a cofactor of relevant enzymatic complexes including the glycine cleave system and 2-ketoacid dehydrogenases. Intervention on LA de novo synthesis or salvage could have pleiotropic deleterious effect in cells, making both pathways attractive for chemotherapy. We show that Trypanosoma cruzi was susceptible to treatment with LA analogues. 8-Bromo-octanic acid (BrO) inhibited the growth of epimastigote forms of both Dm28c and CL Brener strains, although only at high (chemotherapeutically irrelevant) concentrations. The methyl ester derivative MBrO, was much more effective, with EC values one order of magnitude lower (62-66 μM). LA did not bypass the toxic effect of its analogues. Small monocarboxylic acids appear to be poorly internalized by T. cruzi: [C]-octanoic acid was taken up 12 fold less efficiently than [C]-palmitic acid. Western blot analysis of lipoylated proteins allowed the detection of the E2 subunits of pyruvate dehydrogenase (PDH), branched chain 2-ketoacid dehydrogenase and 2-ketoglutarate dehydrogenase complexes. Growth of parasites in medium with 10 fold lower glucose content, notably increased PDH activity and the level of its lipoylated E2 subunit. Treatment with BrO (1 mM) and MBrO (0.1 mM) completely inhibited E2 lipoylation and all three dehydrogenases activities. These observations indicate the lack of specific transporters for octanoic acid and most probably also for BrO and LA, which is in agreement with the lack of a LA salvage pathway, as previously suggested for T. brucei. They also indicate that the LA synthesis/protein lipoylation pathway could be a valid target for drug intervention. Moreover, the free LA available in the host would not interfere with such chemotherapeutic treatments. 10.1016/j.exppara.2018.01.017
Effect of Rearing System on the Straight and Branched Fatty Acids of Goat Milk and Meat of Suckling Kids. Ripoll Guillermo,Alcalde María Jesús,Argüello Anastasio,Córdoba María de Guía,Panea Begoña Foods (Basel, Switzerland) Goat meat is considered healthy because it has fewer calories and fat than meat from other traditional meat species. It is also rich in branched chain fatty acids that have health advantages when consumed. We studied the effects of maternal milk and milk replacers fed to suckling kids of four breeds on the straight and branched fatty acid compositions of their muscle. In addition, the proximal and fatty acid compositions of colostrum and milk were studied. Goat colostrum had more protein and fat and less lactose than milk. Goat milk is an important source of healthy fatty acids such as C18:1 c9 and C18:2 n-6. Suckling kid meat was also an important source of C18:1c9. Dairy goat breeds had higher percentages of monounsaturated fatty acids (MUFAs) and most of the C18:1 isomers but lower amounts of total MUFAs than meat breeds. However, these dairy kids had meat with a lower percentage of conjugated linoleic acid (CLA) than meat kids. The meat of kids fed natural milk had higher amounts of CLA and branched chain fatty acids (BCFAs) and lower amounts of n-6 fatty acids than kids fed milk replacers. Both milk and meat are a source of linoleic, α-linolenic, docosahexaenoic, eicosapentaenoic and arachidonic fatty acids, which are essential fatty acids and healthy long-chain fatty acids. 10.3390/foods9040471
Fragrance material review on methyl dihydrojasmonate. Scognamiglio J,Jones L,Letizia C S,Api A M Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association A toxicologic and dermatologic review of methyl dihydrojasmonate when used as a fragrance ingredient is presented. Methyl dihydrojasmonate is a member of the fragrance structural group ketones cyclopentanones and cyclopentenones. The common characteristic structural element of the group members is a cyclopentanone or cyclopentenone ring with a straight or branched chain alkane or alkene substituent. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for methyl dihydrojasmonate were evaluated then summarized and includes physical properties, acute toxicity, skin irritation, mucous membrane (eye) irritation, skin sensitization, elicitation, phototoxicity, photoallergy, toxicokinetics, repeated dose, reproductive toxicity, and genotoxicity data. A safety assessment of the entire ketones cyclopentanones and cyclopentenones will be published simultaneously with this document; please refer to Belsito et al. (this issue) for an overall assessment of the safe use of this material. 10.1016/j.fct.2012.03.036
A synchronized substrate-gating mechanism revealed by cubic-core structure of the bovine branched-chain alpha-ketoacid dehydrogenase complex. The EMBO journal The dihydrolipoamide acyltransferase (E2b) component of the branched-chain alpha-ketoacid dehydrogenase complex forms a cubic scaffold that catalyzes acyltransfer from S-acyldihydrolipoamide to CoA to produce acyl-CoA. We have determined the first crystal structures of a mammalian (bovine) E2b core domain with and without a bound CoA or acyl-CoA. These structures reveal both hydrophobic and the previously unreported ionic interactions between two-fold-related trimers that build up the cubic core. The entrance of the dihydrolipoamide-binding site in a 30-A long active-site channel is closed in the apo and acyl-CoA-bound structures. CoA binding to one entrance of the channel promotes a conformational change in the channel, resulting in the opening of the opposite dihydrolipoamide gate. Binding experiments show that the affinity of the E2b core for dihydrolipoamide is markedly increased in the presence of CoA. The result buttresses the model that CoA binding is responsible for the opening of the dihydrolipoamide gate. We suggest that this gating mechanism synchronizes the binding of the two substrates to the active-site channel, which serves as a feed-forward switch to coordinate the E2b-catalyzed acyltransfer reaction. 10.1038/sj.emboj.7601444
Insulin regulation of branched chain alpha-keto acid dehydrogenase in adipose tissue. Frick G P,Goodman H M The Journal of biological chemistry The enzyme which oxidizes alpha-keto[1-14C]isocaproate to 14CO2 is activated by incubation of adipose tissue segments with insulin. A 3-fold reduction in the apparent Km of the enzyme for alpha-ketoisocaproate was observed when homogenates of adipose tissue segments treated with insulin were compared to homogenates of control tissues. The enzyme was assayed at various times after homogenization of adipose tissue segments. Relatively small changes were observed in the activity from control or insulin-treated tissues for 30 min after homogenization. The persistence of the insulin effect after homogenization suggests that insulin may cause a covalent modification of the enzyme. The possibility that alpha-ketoisocaproate is oxidized by pyruvate dehydrogenase, which is also stimulated by insulin, is unlikely since the enzyme responsible for oxidation of 14C-labeled branched chain alpha-keto acids can be inactivated by heat at a rate distinct from that of pyruvate dehydrogenase. Moreover, unlabeled branched chain alpha-keto acids inhibit the oxidation of alpha-keto[1-14C]isocaproate but not that of [1-14C]pyruvate. Branched chain alpha-keto acid hydrogenase can be activated by incubation of adipose tissue homogenates in the presence of magnesium chloride and in the absence of ATP. The addition of ATP plus an ATP-regenerating system reverses the activation of the enzyme. The apparent Km of the enzyme is reduced and the Vmax is increased by incubation of tissue extracts under appropriate conditions.
Lipids of heliobacteria are characterised by a high proportion of monoenoic fatty acids with variable double bond positions. Aase B,Jantzen E,Bryn K,Ormerod J Photosynthesis research The fatty acid composition and lipid pattern of six strains of heliobacteria have been analysed. The results were fairly uniform for all strains. Phosphatidyl ethanolamine and phosphatidyl glycerol were the dominating lipids found, with the former as the major one. No glycolipids were detected. The general fatty acid pattern was dominated by acids of chain length C16 to C18. An unusually large proportion of monoenoic acids was seen, with up to four positional isomers for each chain length. Methyl branched (iso) fatty acids were present, but not cyclopropyl or hydroxy fatty acids nor fatty alcohols. 10.1007/BF02184146
Characterization of the cardiac succinylome and its role in ischemia-reperfusion injury. Boylston Jennifer A,Sun Junhui,Chen Yong,Gucek Marjan,Sack Michael N,Murphy Elizabeth Journal of molecular and cellular cardiology Succinylation refers to modification of lysine residues with succinyl groups donated by succinyl-CoA. Sirtuin5 (Sirt5) is a mitochondrial NAD(+)-dependent deacylase that catalyzes the removal of succinyl groups from proteins. Sirt5 and protein succinylation are conserved across species, suggesting functional importance of the modification. Sirt5 loss impacts liver metabolism but the role of succinylation in the heart has not been explored. We combined affinity enrichment with proteomics and mass spectrometry to analyze total succinylated lysine content of mitochondria isolated from WT and Sirt5(-/-) mouse hearts. We identified 887 succinylated lysine residues in 184 proteins. 44 peptides (5 proteins) occurred uniquely in WT samples, 289 (46 proteins) in Sirt5(-/-) samples, and 554 (133 proteins) were common to both groups. The 46 unique proteins in Sirt5(-/-) heart participate in metabolic processes such as fatty acid β-oxidation (Eci2) and branched chain amino acid catabolism, and include respiratory chain proteins (Ndufa7, 12, 13, Dhsa). We performed label-free analysis of the peptides common to WT and Sirt5(-/-) hearts. 16 peptides from 9 proteins were significantly increased in Sirt5(-/-) by at least 30%. The adenine nucleotide transporter 1 showed the highest increase in succinylation in Sirt5(-/-) (108.4 fold). The data indicate that succinylation is widespread in the heart and enriched in metabolic pathways. We examined whether the loss of Sirt5 would impact ischemia-reperfusion (I/R) injury and we found an increase in infarct size in Sirt5(-/-) hearts compared to WT littermates (68.5(+)/-1.1% Sirt5(-/-) vs 39.6(+)/(-) 6.8% WT) following 20min of ischemia and 90-min reperfusion. We further demonstrate that I/R injury in Sirt5(-/-) heart is restored to WT levels by pretreatment with dimethyl malonate, a competitive inhibitor of succinate dehydrogenase (SDH), implicating alteration in SDH activity as causative of the injury. 10.1016/j.yjmcc.2015.09.005
Accumulation of 3-hydroxyisobutyric acid, 2-methyl-3-hydroxybutyric acid and 3-hydroxyisovaleric acid in ketoacidosis. Landaas S Clinica chimica acta; international journal of clinical chemistry 1. Urine and serum samples from patients with ketoacidosis of varying degree and etiology have been examined by gas chromatography and mass spectrometry. 2. In addition to 3-hydroxyisovaleric acid, relatively high concentrations of two analogous hydroxy acids, 3-hydroxyisobutyric acid and 2-methyl-3-hydroxybutyric acid, were found in the urine. 3. There were highly significant positive correlations between the excreted amounts of the three acids. 4. Experiments on rats with isotope-labelled compounds revealed that the acids were formed by the degradation of leucine, isoleucine and valine. 5. The accumulation of the hydroxy acids during ketoacidosis is probably caused by a similar derangement of the metabolism of all three branched-chain amino acids. 10.1016/0009-8981(75)90196-5
Fragrance material review on methyl 3-oxo-2-(pent-2-enyl)cyclopentaneacetate. Scognamiglio J,Jones L,Letizia C S,Api A M Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association A toxicologic and dermatologic review of methyl 3-oxo-2-(pent-2-enyl)cyclopentaneacetate when used as a fragrance ingredient is presented. Methyl 3-oxo-2-(pent-2-enyl)cyclopentaneacetate is a member of the fragrance structural group Ketones Cyclopentanones and Cyclopentenones. The common characteristic structural element of the group members is a cyclopentanone or cyclopentenone ring with a straight or branched chain alkane or alkene substituent. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for methyl 3-oxo-2-(pent-2-enyl)cyclopentaneacetate were evaluated then summarized and includes physical properties data. A safety assessment of the entire Ketones Cyclopentanones and Cyclopentenones will be published simultaneously with this document; please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all ketones cyclopentanones and cyclopentenones in fragrances. 10.1016/j.fct.2012.03.030
Exogenous methyl jasmonate affects genes involved in monoterpene biosynthetic pathway, phyto-biochemical accumulation, and enzymatic activity of Satureja hortensis L. Gene Satureja hortensis L. (SH) is a medicinal and aromatic herb utilized markedly in the food, pharmaceutical, and cosmetic industries because of its specific secondary metabolites (SMs), especially monoterpenoids. However, the impact of elicitors on the expression of monoterpene synthase genes in SH remains unexplored. Therefore, the supreme objective of this research was to elucidate the phyto-biochemical and targeted genes expression responses of SH to the exogenous application of methyl jasmonate (MeJA). Accordingly, having chosen four concentrations of MeJA, they sprayed at the five-leaf stage for two weeks, and then leaves were harvested at two exposure times of 24 and 48 hrs for further analysis, using spectrophotometric, real time-quantitative polymerase chain reaction (RT-qPCR), and gas chromatography-mass spectrometric (GC-MS) methods. The results highlight that not only were the highest contents of phenolic, flavonoids, peroxidase, superoxide dismutase, proline, and malondialdehyde in the elicited SHs but also the highest expression of β-farnesene synthase (BFS) and 1-deoxy-D-xylulose 5-phosphate reductase (DXR) genes together with the highest amount of carvacrol were up-regulated in them compared to their respective control. In conclusion, these findings demonstrate the great industrial potential of MeJA in improving the production of phytochemicals in medicinal plants, particularly in SH. 10.1016/j.gene.2023.147882
Phytanic acid alpha-hydroxylation by bacterial cytochrome P450. Matsunaga I,Sumimoto T,Kusunose E,Ichihara K Lipids Fatty acid alpha-hydroxylase, a cytochrome P450 enzyme, from Sphingomonas paucimobilis, utilizes various straight-chain fatty acids as substrates. We investigated whether a recombinant fatty acid alpha-hydroxylase is able to metabolize phytanic acid, a methyl-branched fatty acid. When phytanic acid was incubated with the recombinant enzyme in the presence of H2O2, a reaction product was detected by gas chromatography, whereas a reaction product was not detected in the absence of H2O2. When a heat-inactivated enzyme was used, a reaction product was not detected with any concentration of H2O2. Analysis of the methylated product by gas chromatography-mass spectrometry revealed a fragmentation pattern of 2-hydroxyphytanic acid methyl ester. By single-ion monitoring, the mass ion and the characteristic fragmentation ions of 2-hydroxyphytanic acid methyl ester were detected at the retention time corresponding to the time of the product observed on the gas chromatogram. The Km value for phytanic acid was approximately 50 microM, which was similar to that for myristic acid, although the calculated Vmax for phytanic acid was about 15-fold lower than that for myristic acid. These results indicate that a bacterial cytochrome P450 is able to oxidize phytanic acid to form 2-hydroxyphytanic acid.
Serum branched chain amino and keto acid response to fasting in humans. Schauder P,Herbertz L,Langenbeck U Metabolism: clinical and experimental Eight healthy individuals were fasted for 72 hours. The concentrations of the branched chain keto acids (BCKA), branched chain amino acids (BCAA), C peptide, and glucagon were determined in peripheral venous blood. alpha-ketoisocaproic acid, alpha-keto-beta-methyl-n-valeric acid, and alpha-ketoisovaleric acid increased significantly within 36 hours along with the corresponding amino acids. After 60 hours of starvation, the concentrations of BCKA and BCAA declined despite the fact that the subjects were still in the fasting state. These changes were accompanied by a decrease in the concentrations of C peptide and an increase in glucagon levels. It is suggested that in starving man insulinopenia may contribute to the rise in BCKA concentrations and that the increase in BCKA may be a mechanism to reduce proteolysis.
Degradation of branched-chain amino acids and their derived 2-oxo acids and fatty acids in human and rat heart and skeletal muscle. Wagenmakers A J,Veerkamp J H Biochemical medicine
Mevalonic acid is partially synthesized from amino acids in Halobacterium cutirubrum: a 13C nuclear magnetic resonance study. Ekiel I,Sprott G D,Smith I C Journal of bacteriology 13C nuclear magnetic resonance revealed an unusual pathway for the biosynthesis of lipids in Halobacterium cutirubrum and H. halobium. Mevalonic acid was not synthesized from three acetyl-coenzyme A molecules, as has been suggested previously, and the branch-methyl and methine carbons in phytanyl chains were derived from neither acetate nor glycerol. Instead, they were supplied by the degradation of amino acids, in particular of lysine. Presumably, two different types of two-carbon fragments were used simultaneously by halobacteria for the biosynthesis of mevalonate. The labeling pattern of squalene supported the above conclusions. Based on these data, a general scheme is proposed to account for the contribution of lysine-to-lipid biosynthesis. 10.1128/jb.166.2.559-564.1986
Potential of Lentibacillus sp. NS12IITR for production of lipids with enriched branched-chain fatty acids for improving biodiesel properties along with hydrocarbon co-production. Singh Noopur,Choudhury Bijan Extremophiles : life under extreme conditions Hypersaline environment is inhabited by array of microbes which have the potential to produce industrially important products. This study explored biomass and lipid production potential of the halophilic bacterium, strain NS12IITR which was isolated from Sambhar Lake, Rajasthan. Sequencing and phylogenetic analysis revealed that the bacterium belonged to genus Lentibacillus. The salient feature of the isolate is its ability to accumulate total cellular lipid up to 18.9 ± 0.45% of dry cell weight. In addition, trans-esterification of extracted lipid yielded 77.6 ± 5.56% of total esters as methyl ester of branched-chain fatty acids (BCFAs). To assess the nature of extracted lipid, lipid sample was fractionated on the silicic acid column, which demonstrated that 49.03 ± 1.35% of the total lipids was neutral in nature. Trans-esterification of the neutral lipid fraction yielded 60.62 ± 4.88% of total esters as methyl ester of BCFAs. Methyl esters of BCFAs were present in trans-esterified products of neutral as well as polar lipid fractions. Furthermore, the isolate produced hydrocarbons both extracellularly (C-C) and intra-cellularly (C-C). The concentration of extracellular hydrocarbon (21.11 ± 0.78 mg/L) synthesized by strain NS12IITR is in close agreement with the yield reported from other hydrocarbon producing bacteria. This is hereby a first report on the co-production of lipids and hydrocarbon from a halophilic bacterium. The production of neutral lipid with high percentage of BCFAs and co-production of hydrocarbons makes the isolate NS12IITR a potential claimant for biofuel production. 10.1007/s00792-018-1043-6
Determination of molecular species composition of C80 or longer-chain alpha-mycolic acids in Mycobacterium spp. by gas chromatography-mass spectrometry and mass chromatography. Kaneda K,Naito S,Imaizumi S,Yano I,Mizuno S,Tomiyasu I,Baba T,Kusunose E,Kusunose M Journal of clinical microbiology The molecular species composition of alpha-mycolic acids ranging from C68 to C86 in 13 rapidly growing and 12 slowly growing mycobacterial species was determined by gas chromatography, gas chromatography-mass spectrometry, and mass chromatography. In gas chromatographic analysis, the molecular species of alpha-mycolic acids were well separated as trimethylsilyl ether derivatives of the methyl esters, according to their total carbon numbers. The total carbon and double-bond numbers of mycolic acids at each peak on gas chromatograms were determined from the [M]+, [M - 15]+, and [M - 90]+ ions on the mass spectrum, and straight and branched chain structures were identified by the mass fragment ions [A]+, due to C2--C3 cleavage [R-CH-O-Si(CH3)3]+, and [B]+, due to C3--C4 cleavage [(CH3)3-Si-O-CH-CH(R')-COOCH3]+. The concentration of odd- and even-carbon-numbered mycolic acids, which often overlap each other on gas chromatograms, and the composition of three homologous mycolic acids with different alpha units (C22:0, C24:0, and C26:0) were clearly determined by mass chromatography monitoring [M - 15]+ ions and [B - 29]+ ions, respectively. The molecular species composition of alpha-mycolic acids and their average carbon numbers (av. cn.) as a simple expression of the composition were calculated from the mass chromatograms. Each mycobacterial species examined was demonstrated to possess a characteristic profile of alpha-mycolic acid composition, and based on this the species were classified approximately into eight groups: C68 to C76 (av. cn. 72), dienoic, possessing a C20 alkyl branch at the 2 position (C22 alpha-unit) for Mycobacterium diernhoferi and Mycobacterium sp. strain 3707, a chromogenic rapid grower; C72 to C78 (av. cn. 75), dienoic with both C22 and C24 alpha units, containing a small or a large amount of odd-carbon-numbered molecules, for M. vaccae, M. rhodesiae, and M. phlei (chromogenic rapid growers); C72 to C80 (av. cn. 75 to 77), dienoic with C24 alpha-unit, containing a moderate or a large amount of odd-carbon-numbered molecules, for M. smegmatis, M. chitae, M. chelonae (M. chelonei), and M. fortuitum (nonchromogenic rapid growers); C78 to C82 (av. cn. 80), even-carbon-numbered dienoic with C24 alpha unit for M. agri and M. thermoresistible (rapid growers); C75 to C81 (av. cn. 77 to 79), odd-carbon-numbered dienoic with C24 alpha unit for M. nonchromogenicum complex (M. nonchromogenicum, M. terrae, and "M. novum") (slow growers); (vi) C76 to C84 (av. cn. 79 to 81), even-carbon-numbered dienoic with C24 alpha unit for MAIS complex including M. scrofulaceum, M. avium, and M. intracellulare (slow growers); (vii) C72 to C80 (av. cn. 77 to 79), even-carbon-numbered dienoic with C24 alpha unit for M. szulgai, M. gordonae, and M. kansasii (chromogenic slow growers); and (viii) C76 to C86 (av. cn. 79 to 81), even-carbon-numbered dienoic with C26 alpha unit M. bovis Ravenol and BCG and M. tuberculosis H37Rv. This study demonstrated that gas chromatography-mass spectrometric analysis of the molecular species composition of alpha-mycolic acid can give rapid, important, and very precise information for the identification of pathogenic and nonpathogenic mycobacterial species. 10.1128/jcm.24.6.1060-1070.1986
Regulation of the branched chain alpha-ketoacid pathway in liver. Corkey B E,Martin-Requero A,Walajtys-Rode E,Williams R J,Williamson J R The Journal of biological chemistry