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Results for “Butyryl-CoA Dehydrogenase”

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At least 19 recordsLinked to original sources
PubMed1975

[The occurrence of a reductase of delta2-carboxylic acids in Clostridium kluyveri with a stereospecificity different from that of butyryl-CoA dehydrogenase (author's transl)].

A Clostridia strain (R-strain) which hydrogenates tiglinate (1b) and alpha-methylcinnamate (1c) in the presence of hydrogenase gas in 2H2O to (2R, 3S)2-methyl-[2,3-2H]butyrate (5b, H = 2H) and (alphaR, betaR)alpha-methyl[alpha,beta-2H]dihydrocinnamate (5c, H = 2H), respectively, was isolated. The configuration at C-3 was determined by 1H-NMR spectroscopy in the presence of Eu(fod)3. The stereochemistry of this hydrogenation is the mirror image of that which has been determined with intact cells of another strain of Clostridium kluyveri (S-strain). In the presence of hydrogen gas, the R-strain hydrogenates crotonate in 2H2O to butyrate with the following deuterium distribution: C-2, 1.85; C-3, 1.35; and C-4, 0.63 deuterium atoms. Crotonate seems to be the substrate of two reductases with sterically different actions. Tiglinate (1b) and alpha-methylcinnamate, however, are hydrogenated only by that reductase which is different from the butyryl-CoA dehydrogenase.

Butyrates↗
PubMed1975

Electron-transferring flavoprotein of Peptostreptococcus elsdenii that functions in the reduction of acrylyl-coenzyme A.

In Peptostreptococcus elsdenii, a three-component flavoprotein electron transfer system catalyzes the oxidation of lactate and the reduction of crotonyl-coenzyme A (CoA). Spectral evidence showed that D-lactate dehydrogenase, when reduced by D-lactate, was able to reduce butyryl-CoA dehydrogenase, but only in the presence of the electron-transferring flavoprotein. Reduced nicotinamide adenine dinucleotide could replace reduced D-lactate dehydrogenase. A reconstituted system, containing the three partially purified enzymes, excess D-lactate, and a limiting amount of crotonyl-CoA, reduced the crotonyl-CoA to butyryl-CoA, but only if all components were present. The electron-transferring flavoprotein activity, purified 22-fold, was separated into two major flavoprotein components, A and B, after polyacrylamide gel electrophoresis. Elution of the proteins and subsequent kinetic assays of the eluates showed that component B catalyzes the reduction of butyryl-CoA dehydrogenase by reduced D-lactate dehydrogenase, whereas component A does not. Both A and B catalyzed the reduction of butyryl-CoA dehydrogenase by reduced nicotinamide adenine dinucleotide. The results suggest that the D-lactate dehydrogenase-dependent reduction involves a heretofore unrecognized component of the electron-transferring protein group which may utilize an unusual flavin, 6-hydroxy-7,8-dimethyl-10-(ribityl-5'-adenosine diphosphate)-isoalloxazine.

Acrylates↗
PubMed1976

Selective inhibition of acyl-CoA dehydrogenases by a metabolite of hypoglycin.

Extracts of liver mitochondria from donor rats given hypoglycin, the toxic amino acid from the ackee plant (Blighia sapida) showed drastically reduced levels of acyl-CoA dehydrogenase activity with butyryl-CoA as substrate. Activity with octanoyl- and palmitoyl-CoA was unaffected. Evidence that the active agent is methylenecyclopropylacetyl-CoA, a hypoglycin metabolite, was obtained by observing effects of the compound on a partially purified enzyme mixture prepared from rabbit liver. At 13 muM concentration, it strongly inhibited butyryl-CoA dehydrogenase (EC 1.3.99.2) with butyryl-CoA as substrate; it was far less effective with palmitoyl-CoA as substrate for the other similar enzymes present in the preparation. Unlike normal substrates of the acyl-CoA dehydrogenases, the compound itself, and not a reaction product, is inhibitory. The observed effect is consistent with quite general inhibition of fatty acid beta-oxidation by hypoglycin.

Alanine↗
PubMed1978

A reappraisal of the reaction of butyryl-coenzyme A dehydrogenase with phenylmercuric acetate. Evidence that de-greening involves a reaction of the tightly bound thioester.

Phenylmercuric acetate reversibly de-greens butyryl-CoA dehydrogenase from Megasphaera elsdenii, abolishing the absorption band at 710nm. The view that this is a result of modification of a protein thiol group is re-examined in the light of the following new observations. (i) After treatment with phenylmercuric acetate, the enzyme's ability to be re-greened by addition of thiols was not decreased by gel filtration or precipitation with (NH(4))(2)SO(4). (ii) Phenylmercuric acetate caused the same extent of de-greening whether added in a few large amounts or many small ones. The overall time taken for de-greening was, however, greatly extended when many small additions were made. (iii) In Tris/acetate buffer, pH7.5, 3.5mol of phenylmercuric acetate/mol of enzyme subunit was required for complete de-greening, compared with only 2.5mol/mol in phosphate buffer, pH7. (iv) None of the groups that react with phenylmercuric acetate is accessible to iodoacetate or iodoacetamide. (v) On a molar basis dithiothreitol, mercaptoethanol and CoA are equally effective in re-greening the enzyme. (vi) Provided that phenylmercuric acetate is not present in excess, the de-greened enzyme forms normal and stable complexes with crotonyl-CoA and acetoacetyl-CoA. (vii) When a small excess of phenylmercuric acetate is present, full stable development of the enzyme-acetoacetyl-CoA complex requires addition of several mol of acetoacetyl-CoA/mol of enzyme subunit. (viii) The ability of de-greened enzyme to be immediately re-greened by an excess of thiol declines with time, more rapidly at pH6 than at pH7 or 8, but at all three pH values the instantaneous re-greening was followed by a slow phase of further increase in A(710). This further recovery was most extensive and most rapid at pH8. These findings are reminiscent of the previously described reversible decline in the re-greening capacity of a protein-free acid extract of green butyryl-CoA dehydrogenase. It is concluded that the likely cause of de-greening is chemical modification of the tightly bound thioester rather than a protein thiol group. The reversibility would be explained if the thioester exists on the surface of the enzyme in equilibrium with free CoA and a lactone, or if the acyl group is readily and reversibly transferred from the thiol of CoA to a protein side chain.

Acyl Coenzyme A↗
PubMed1979

Effect of clofibrate treatment on acylcarnitine oxidation in isolated rat liver mitochondria.

The oxidation of palmitoyl- and octanoylcarnitine in liver mitochondria from normal and clofibrate-treated male rats was studied by measuring the ADP-stimulated oxygen consumption and acetyl group production (the sum of formed ketone bodies, acetylcarnitine and citrate). In the absence of malate the treatment approximately doubled the rate of acylcarnitine oxidation. In normal mitochondria the acetyl groups consisted almost totally of ketone bodies. The clofibrate-induced increase in acetyl group production was attributable to enhanced rates of ketone body and acetylcarnitine formation. The observed increase in acylcarnitine oxidation was associated with an elevated beta-hydroxybutyrate: acetoacetate ratio, reflecting an increased mitochondrial NADH:NAD+ ratio. In normal mitochondria the addition of malate in the presence of fluorocitrate doubled the rate of beta oxidation by forming citrate. The beta oxidation in mitochondria from clofibrate-treated rats was virtually unresponsive to added malate. The clofibrate-induced increase in ketogenesis was confirmed in disintegrated mitochondria. The treatment approximately doubled the rate of ketone body production from acetyl-CoA in disrupted organelles. The enhanced capacity of ketogenesis was accompanied by increased activity of the specific acetoacetyl-CoA thiolase (EC 2.3.1.8), which is the first step enzyme of the pathway. Clofibrate administration also increased the activities of general oxoacyl-CoA thiolase (EC 2.3.1.16), palmitoyl-CoA dehydrogenase (EC 1.3.99.3), and butyryl-CoA dehydrogenase (EC 1.3.99.2), which all take part in the beta oxidation of fatty acids.

Acetoacetates↗
PubMed1992

Effect of L-penicillamine hydantoin, an analogue of glutathione, on rat liver glutathione peroxidase, reductase and transferase reactions.

In soluble fractions prepared from rat liver homogenates, L-penicillamine hydantoin appeared to be, on the basis of SH consumption measurements, a substrate for glutathione peroxidase but not transferase reactions. When glutathione is incubated with rat liver soluble proteins in the presence of penicillamine hydantoin, formation of oxidized glutathione is inhibited. Calculations from Lineweaver-Burk plots point out that inhibition by L-penicillamine hydantoin of the peroxide-dependent oxidations of glutathione is mixed, since both apparent Km and Vmax values are modified. Preincubation of rat liver soluble proteins with L-penicillamine hydantoin led to a progressive inactivation of glutathione peroxidase. The kinetics of this inactivation process with respect to time and inactivator concentration were studied. Inclusion in the preincubation mixture of SH-containing molecules such as dithiothreitol, L-cysteine or glutathione protected the enzyme against inactivation. However, none of these molecules and neither hydantoin, Triton X-100, phenol, nor dialysis could reverse the enzyme from inactivated to activated form. Mitochondrial glutathione peroxidase was inhibited and inactivated by L-penicillamine hydantoin to the same extent as its cytosolic counterpart. Modifications by penicillamine hydantoin of various subcellular markers enzymes (lactate dehydrogenase, N-acetyl beta-glucosaminidase, arylsulfatase C, butyryl-CoA dehydrogenase, lauryl-CoA and glycolate oxidases) were of weak amplitude consisting of either inhibition, inactivation or stimulation.

Animals↗
PubMed1992

Lipid storage myopathy in multiple acyl-CoA dehydrogenase deficiency: an adult case.

A 25-year-old woman had been complaining of episodes of muscle weakness, nausea and vomiting since the age of 10. Muscle biopsy showed free fatty acid accumulation and mitochondrial abnormalities. Mitochondrial DNA appeared to be normal at Southern analysis. Biochemical investigations demonstrated: glutaric aciduria type II, decreased levels of carnitine in liver and values at the lower level of normal in muscle, increased muscle carnitine palmitoyl transferase activity, partial cytochrome c oxidase and succinate cytochrome reductase deficiency in muscle homogenate. In isolated muscle mitochondria, cytochromes aa3, b and c were partially decreased, butyryl-CoA dehydrogenase and palmitoyl-CoA dehydrogenase activities were 10 and 54% of the normal, respectively. Muscle cell cultures did not show lipid storage. Low-lipid diet reduced critical episodes and lipid storage in muscle biopsy.

Acyl-CoA Dehydrogenases↗
PubMed1979

Inhibition of gluconeogenesis in isolated rat liver cells by methylenecyclopropylpyruvate (ketohypoglycin).

1. In isolated rat liver cells, hypoglycin is a less effective inhibitor of gluconeogenesis than its transamination product, methylenecyclopropylpyruvate (ketohypoglycin). 2. Methylenecyclopropylpyruvate at 0.3 mM inhibits gluconeogenesis from all substrates tested, except fructose. 3. Methylenecyclopropylpyruvate does not affect 14CO2 release from [1(-14)C]palmitate, but, in the absence of lactate, inhibits ketogenesis and causes a decrease in the [beta-hydroxybutyrate]/[acetoacetate] ratio. These effects are masked when lactate (10 mM) is present. 4. In the presence of lactate and palmitate, 0.3 mM-methylenecyclopropylpyruvate produces a fall in total acid-soluble CoA and a relative increase in short-chain acyl-CoA at the expense of CoA and acetyl-CoA without changing the ATP, ADP and aspartate contents or the [lactate]/[pyruvate] ratio. 5. Many of the effects of methylenecyclopropylpyruvate observed are consistent with inhibition of butyryl-CoA dehydrogenase and of specific CoA-dependent enzymes involved in gluconeogenesis.

Animals↗
PubMed1990

Identification of two variant short chain acyl-coenzyme A dehydrogenase alleles, each containing a different point mutation in a patient with short chain acyl-coenzyme A dehydrogenase deficiency.

Two distinct mutant alleles of the precursor (p) short chain acyl-CoA dehydrogenase (SCAD) gene were identified in a SCAD-deficient patient (YH2065) using the polymerase chain reaction to amplify cDNA synthesized from total RNA from her fibroblasts. Cells from this patient had previously been shown to synthesize a labile variant SCAD in contrast to the normal stability of variant SCADs in two other SCAD-deficient cell lines (Naito, E., Y. Indo, and K. Tanaka. 1989. J. Clin. Invest. 84:1671-1674). In the present study, both mutant alleles of YH2065 were found to contain a C----T transition, one at position 136 and the other at position 319 of the coding region of pSCAD cDNA. Clones of cDNA amplified from this region showed only one of the C----T transitions, indicating that each mutation was derived from different pSCAD alleles. Each of these mutations altered a known restriction endonuclease site, and restriction analysis of additional cDNA clones from amplified mutant cDNA and Southern blotting of mutant genomic DNA confirmed the presence of two unique mutant alleles in YH2065, indicating YH2065 is a compound heterozygote. These C----T transitions result in the substitution of Arg-22 and Arg-83 of the mature SCAD with Trp and Cys, respectively.

Acyl-CoA Dehydrogenases↗
PubMed1992

Purification and properties of 3-hydroxybutyryl-coenzyme A dehydrogenase from Clostridium beijerinckii ("Clostridium butylicum") NRRL B593.

The enzyme 3-hydroxybutyryl-coenzyme A (CoA) dehydrogenase has been purified 45-fold to apparent homogeneity from the solvent-producing anaerobe Clostridium beijerinckii NRRL B593. The identities of 34 of the N-terminal 35 amino acid residues have been determined. The enzyme exhibited a native M(r) of 213,000 and a subunit M(r) of 30,800. It is specific for the (S)-enantiomer of 3-hydroxybutyryl-CoA. Michaelis constants for NADH and acetoacetyl-CoA were 8.6 and 14 microM, respectively. The maximum velocity of the enzyme was 540 mumol min-1 mg-1 for the reduction of acetoacetyl-CoA with NADH. The enzyme could use either NAD(H) or NADP(H) as a cosubstrate; however, kcat/Km for the NADH-linked reaction was much higher than the apparent value for the NADPH-linked reaction. Also, NAD(H)-linked activity was less sensitive to changes in pH than NADP(H)-linked activity was. In the presence of 9.5 microM NADH, the enzyme was inhibited by acetoacetyl-CoA at concentrations as low as 20 microM, but the inhibition was relieved as the concentration of NADH was increased, suggesting a possible mechanism for modulating the energy efficiency during growth.

Amino Acid Sequence↗
PubMed1975

Substrate stereochemistry of the acetyl-CoA acetyltransferase reaction.

1. A specimen of symmetrically tritiated 3S-3-hydroxy[2-3H2]butyryl-CoA was prepared from acetoacetyl-CoA by incubation in tritiated water, followed by enzymic reduction using 3S-specific 3-hydroxyacyl-CoA dehydrogenase. In addition, a specimen of dideuterated, racemic 3RS-3-hydroxy-[2-2H2]butyryl-CoA was prepared chemically from 3RS-3-hydroxy[2-2H2]butyric acid. 2. These acyl-CoA derivatives were incubated respectively with deuterium oxide and tritated water in presence of enoyl-CoA hydratase. Stereospecifically tritiated compounds, respectively 2S,3S-3-hydroxy[2-2H1,3H1]butyryl-CoA and 2R,3S-3-hydroxy[2-1H1,3H1]butyryl-CoA (plus 3R-diastereomer) were formed and isolated. 3. 3S-3-Hydroxy[2-3H2]butyryl-CoA and the 3S-[2-3H2,3-14C]-labelled material were also prepared as described in the preceding paper. The latter substrate was used to establish conditions in which little loss of tritium would occur (found; about 7%) on cleavage to acetyl-CoA in the presence of 3-hydroxyacyl-CoA dehydrogenase and acetyl-CoA acetyltransferase. Little loss of tritium indicates a small degree of racemization of the stereospecifically 2-tritiated 3-hydroxyacyl-CoA derivatives at the level of transiently formed acetoacetyl-CoA and acetyl-CoA. This ensures high optical purity of the chiral acetates generated from the stereospecifically tritiated hydroxybutyryl-CoA specimens listed in paragraph (2). 4. These two acyl-CoA derivatives and the symmetrically tritiated 3S-3-hydroxy[2-3H2]butyryl-CoA listed in paragraph (3) were converted to the acetates enzymically in the sequence hydroxy-butyryl-CoA leads to acetoacetyl-CoA leads to acetyl-CoA leads to acetate. The isolated acetates were assayed for chirality by conversion to the malates and fumarates as usual. 5. The malate formed from 3S-3-hydroxy[2-3H2]butyryl-CoA on incubation with fumarase lost nearly 50%, that derived from 2R,3S-3-hydroxy[2-2H1,3H1]butyryl-CoA (plus 3R-diastereomer) retained about 26% and that derived from 2S,3S-3-hydroxy[2-1H1,3H1]butyryl-CoA retained about 78% of its total tritium content. 6. It was concluded that the detachment of acetyl-CoA from acetoacetyl-CoA on acetyl-CoA acetyltransferase occurs with inversion of configuration at the methylene group which becomes methyl.

Acetoacetates↗
PubMed1992

Short-chain acyl-coenzyme A dehydrogenase activity, antigen, and biosynthesis are absent in the BALB/cByJ mouse.

BALB/cByJ (J) mice have short-chain acyl-CoA dehydrogenase (SCAD) deficiency and an organic aciduria similar to that of human SCAD deficiency. [9,10(n)-3H]- and [15,16(n)-3H]palmitate oxidations in J mouse fibroblasts were 96 and 35% of control, respectively, consistent with an isolated SCAD defect. Acyl-CoA dehydrogenase activities were assayed in muscle and fibroblast mitochondria from BALB/cBy controls (Y) and SCAD-deficient J mice. Medium-chain acyl-CoA dehydrogenase (MCAD) activities were comparable in both J and Y mice from all tissues. In the presence of MCAD antiserum, SCAD activities in J mice were undetectable in both tissues. Apparent Km and Vmax values in liver mitochondria suggested a somewhat increased affinity of MCAD for butyryl-CoA in J mice, as compared with MCAD from other species. Immunoblot studies using mitochondria revealed identical apparent SCAD molecular weight in liver, muscle, and fibroblasts from Y mice and no detectable SCAD antigen in J mice; MCAD antigen was detected in comparable amounts from both Y and J mice. Radiolabeling and immunoprecipitation studies in J mouse fibroblasts revealed no SCAD synthesis, but normal MCAD synthesis. These data argue against the existence of tissue-specific SCAD isoforms in the mouse and confirm that this mouse strain is a model for the human organic aciduria resulting from this beta-oxidation defect.

Acyl-CoA Dehydrogenase↗
PubMed1975

Short-chain fatty acid synthesis in brain. Subcellular localization and changes during development.

Acetyl-CoA synthase (EC 6.2.1.1), Propionyl-CoA synthase (EC 6.2.1.-) and butyryl-CoA synthase (EC 6.2.1.2) were measured in subcellular fractions prepared by primary and density-gradient fractionation from adult rat brain by a method resulting in recoveries close to 100%. Most of the activity of the three enzymes was recovered in the crude mitochondrial fraction. On subfractionation of this crude mitochondrial fraction with continuous sucrose density gradients, most of the activity of the three enzymes was found at a higher density than NAD+-isocitrate dehydrogenase and at about the same density as glutamate dehydrogenase, confirming earlier reported data for acetyl-CoA synthase. The finding that propionyl-CoA synthase and butyryl-CoA synthase had about the same distribution in the gradients as acetyl-CoA synthase adds support to the hypothesis that mitochondria involved in the metabolism of these short-chain fatty acids (all three of which have been shown to result in a rapid and high labelling of glutamine in vivo) form a distinct subpopulation of the total mitochondrial population. The three synthase activities were found to differ from each other in their rate of change and their subcellular localization during rat brain development. This, in combination with the observation that in gradients of adult brain preparations the three activities did not completely overlap, suggests that the three synthase activities are not present in the same proportion to each other in the same subpopulation (s) of mitochondria in the brain.

Acetate-CoA Ligase↗
PubMed1991

The effect of ligand binding on the proteolytic pattern of methylmalonate semialdehyde dehydrogenase.

Native rat liver methylmalonate semialdehyde dehydrogenase was proteolyzed by lysylendopeptidase C, chymotrypsin, and trypsin to generate different cleavage fragments of molecular masses: 50, 8, 55, 44, 39, 53, 45, and 40 kDa. A proteolytic cleavage map of MMSDH was constructed based on sequencing data and a comparison of appearance and degradation rates of the different protein fragments as shown by SDS-PAGE. NAD+ was highly effective as a protector against proteolysis in both the N-terminal and the C-terminal parts of the intact enzyme. NADH did not efficiently protect the intact enzyme; however, it stabilized proteolytic fragment L50 from further degradation. This suggests that the NAD(+)-binding domain is not destroyed by cleavage of the N-terminal part of MMSDH. CoA had no effect on the proteolytic cleavage patterns of MMSDH. However, CoA esters reduced the protective effect of NAD+ with an order of effectiveness of acetyl-CoA greater than propionyl-CoA greater than butyryl-CoA. p-Nitrophenyl acetate, substrate for esterase activity by the enzyme, partially prevented the protective effect of NAD+ against proteolysis. These results suggest that S-acylation of the enzyme prevents a stabilizing conformational change induced in MMSDH by NAD+ binding.

Aldehyde Oxidoreductases↗
PubMed1979

Ethylmalonic-adipic aciduria. In vivo and in vitro studies indicating deficiency of activities of multiple acyl-CoA dehydrogenases.

The mechanisms underlying ethylmalonic-adipic aciduria were studied in a 5-yr-old girl. Oxidation of radioactive substrates by cultured skin fibroblasts from the proband and asymptomatic family members was also determined and compared to that by normal fibroblasts and that by cells from a patient with glutaric aciduria type II. Feeding medium-chain triglycerides promptly induced vomiting and lethargy accompanied by a pronounced increase of urinary ethylmalonate. Significant increases of serum isovalerate and urinary isovalerylglycine were observed after leucine feeding, but urinary glutarate increased only slightly after lysine feeding. Thus, the results from clinical investigation remained equivocal as to whether pathways other than fatty acid oxidation were blocked in our patient. Oxidation of [1-(14)C]butyrate by cultured skin fibroblasts from the proband was reduced to 14% of control. In vitro oxidation of [2-(14)C]lysine and [2-(14)C]leucine was also reduced to 28 and 23% of control, respectively. Much more severe reduction in oxidation of these three substrates (3, 9, and 9%, respectively) was observed in glutaric aciduria type II cells. These results indicated that in the proband, degradative pathways of fatty acids, lysine, and leucine are blocked at the steps of butyryl-CoA, glutaryl-CoA, and isovaleryl-CoA dehydrogenases, respectively, as in the case of glutaric aciduria type II. Because activities of multiple acyl-CoA dehydrogenases are reduced, a deficiency of electron-transferring flavoprotein, which serves as a hydrogen-acceptor for these dehydrogenases, is postulated as the underlying mechanisms of these two diseases, but a genetic heterogeneity was indicated by significant differences in the residual activities in these two types of cells. The hypothesis of more than one mutant allele of an autosomal recessive gene was also suggested by the study on cells from asymptomatic members of the family.

Acidosis↗
PubMed1992

NADPH-dependent beta-oxidation of unsaturated fatty acids with double bonds extending from odd-numbered carbon atoms.

The mitochondrial metabolism of 5-enoyl-CoAs, which are formed during the beta-oxidation of unsaturated fatty acids with double bonds extending from odd-numbered carbon atoms, was studied with mitochondrial extracts and purified enzymes of beta-oxidation. Metabolites were identified spectrophotometrically and by high performance liquid chromatography. 5-cis-Octenoyl-CoA, a putative metabolite of linolenic acid, was efficiently dehydrogenated by medium-chain acyl-CoA dehydrogenase (EC 1.3.99.3) to 2-trans-5-cis-octadienoyl-CoA, which was isomerized to 3,5-octadienoyl-CoA either by mitochondrial delta 3,delta 2-enoyl-CoA isomerase (EC 5.3.3.8) or by peroxisomal trifunctional enzyme. Further isomerization of 3,5-octadienoyl-CoA to 2-trans-4-trans-octadienoyl-CoA in the presence of soluble extracts of either rat liver or rat heart mitochondria was observed and attributed to a delta 3,5,delta 2,4-dienoyl-CoA isomerase. Qualitatively similar results were obtained with 2-trans-5-trans-octadienoyl-CoA formed by dehydrogenation of 5-trans-octenoyl-CoA. 2-trans-4-trans-Octadienoyl-CoA was a substrate for NADPH-dependent 2,4-dienoyl-CoA reductase (EC 1.3.1.34). A soluble extract of rat liver mitochondria catalyzed the isomerization of 2-trans-5-cis-octadienoyl-CoA to 2-trans-4-trans-octadienoyl-CoA, which upon addition of NADPH, NAD+, and CoA was chain-shortened to hexanoyl-CoA, butyryl-CoA, and acetyl-CoA. Thus we conclude that odd-numbered double bonds, like even-numbered double bonds, can be reductively removed during the beta-oxidation of polyunsaturated fatty acids.

Acetyl-CoA C-Acyltransferase↗
PubMed1975

Substrate stereochemistry of the enoyl-CoA hydratase reaction.

1. A specimen of stereospecifically 2-tritiated 3-hydroxybutyric acid was prepared by hydroboration of ethyl crotonate. It was assumed that the hydroboration reaction took a syn course and hence that (2R,3S) plus (2S,3R)-3-hydroxy[2 minus 3H1]butyric acid was formed after oxidation and hydrolysis. 2. 3RS-3-Hydroxy[2 minus 3H2]butyric acid, symmetrically tritiated at C-2, was prepared by isotopic exchange of ethyl acetoacetate in tritiated water, followed by reduction and hydrolysis. 3. The 3R-enantiomers of the acids listed under paragraphs (1) and (2) were destroyed enzymically by use of 3R-specific 3-hydroxybutyrate dehydrogenase and the residual 3S-enantiomers were isolated. 4. The resulting specimens of 2R,3S-3-hydroxy[2 minus 3H1]butyric acid and 3S-3hydroxy[2 minus 3H2]-butyric acid were converted chemically to the acyl-CoA derivatives. These were incubated with enoyl-CoA hydratase. 5. In the presence of the enoyl-CoA hydratase symmetrically labelled 3S-3-hydroxy[2 minus 3H2]BUTYRYL-CoA lost nearly 50% of its tritium label; 2R,3S-3hydroxy [2-3-H1]butyryl-CoA lost about 78%. 6. It was concluded that the elimination of the elements of water from 3-hydroxybutyryl-CoA on the hydratase occurs stereospecifically with syn geometry.

Acetoacetates↗
PubMed1979

Enzymology of butyrate formation by Butyrivibrio fibrisolvens.

Butyrivibrio fibrisolvens is a major butyrate-forming species in the bovine and ovine rumen. The enzymology of butyrate formation from pyruvate was investigated in cell-free extracts of B. fibrisolvens D1. Pyruvate owas oxidized to acetylcoenzyme A (CoA) in the presence of CoA.SH and benzyl viologen or flavin nucleotides. The bacterium uses thiolase, beta-hydroxybutyryl-CoA dehydrogenase, crotonase, and crotonyl-CoA reductase to form butyryl-CoA from acetyl-CoA. Reduction of acetoacetyl-CoA to beta-hydroxybutyryl-CoA was faster with NADH than with NADPH. Crotonyl-CoA was reduced to butyryl-CoA by NADH, but not by NADPH, only in the presence of flavin nucleotides. Reduction of flavin nucleotides by NADH was much slower than the flavin-dependent reduction of crotonyl-CoA. This indicates that flavoproteins rather than free flavin participated in the reduction of crotonyl-CoA. Butyryl-CoA was converted to butyrate by phosphate butyryl transferase and butyrate kinase.

3-Hydroxyacyl CoA Dehydrogenases↗