Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.3.1.8 (acyl-CoA dehydrogenase)
785 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The beta-oxidation of valproic acid (2-propylpentanoic acid), an anticonvulsant drug with hepatotoxic side effects, was studied with subcellular fractions of rat liver and with purified enzymes of beta-oxidation. 2-Propyl-2-pentenoyl-CoA, a presumed intermediate in the beta-oxidation of valproic acid, was chemically synthesized and used to demonstrate that enoyl-CoA hydratase or crotonase catalyzes its hydration to 3-hydroxy-2-propylpentanoyl-CoA. The latter compound was not acted upon by soluble L-3-hydroxyacyl-CoA dehydrogenases from mitochondria or peroxisomes but was dehydrogenated by an NAD(+)-dependent dehydrogenase associated with a mitochondrial membrane fraction. The product of the dehydrogenation, presumably 3-keto-2-propylpentanoyl-CoA, was further characterized by fast bombardment mass spectrometry. 3-Keto-2-propylpentanoyl-CoA was not cleaved thiolytically by 3-ketoacyl-CoA thiolase or a mitochondrial extract but was slowly degraded, most likely by hydrolysis. The availability of 2-propylpentanoyl-CoA (valproyl-CoA) and its beta-oxidation metabolites facilitated a study of valproate metabolism in coupled rat liver mitochondria. Mitochondrial metabolites identified by high-performance liquid chromatography were 2-propylpentanoyl-CoA, 3-keto-2-propylpentanoyl-CoA, 2-propyl-2-pentenoyl- CoA, and trace amounts of 3-hydroxy-2-propylpentanoyl-CoA. It is concluded that valproic acid enters mitochondria where it is converted to 2-propylpentanoyl-CoA, dehydrogenated to 2-propyl-2-pentenoyl-CoA by 2-methyl-branched chain acyl-CoA dehydrogenase, and hydrated by enoyl-CoA hydratase to 3-hydroxy-2-propylpentanoyl-CoA.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Mitochondrial metabolism of valproic acid. 198 37

Respiration-linked oxidation of 3-hydroxybutyryl-CoA, crotonyl-CoA and saturated fatty acyl (C4, C8 and C14)-CoA esters was studied in different mitochondrial preparations. Oxidation of acyl-CoA esters was poor in intact mitochondria; however, it was significant, as well as, NAD+ and CoA-dependent in gently and in vigorously sonicated mitochondria. The respiration-linked oxidation of crotonyl-CoA and 3-hydroxybutyryl-CoA proceeded at much higher rates (over 700%) in gently disrupted mitochondria than in completely disrupted mitochondria. The redox dye-linked oxidation of crotonyl-CoA (with inhibited respiratory chain) was also higher in gently disrupted mitochondria (149%) than in disrupted ones. During the respiration-linked oxidation of 3-hydroxybutyryl-CoA the steady-state NADH concentrations in the reaction chamber were determined, and found to be 8 microM in gently sonicated and 15 microM in completely sonicated mitochondria in spite of the observation that the gently sonicated mitochondria oxidized the 3-hydroxybutyryl-CoA much faster than the completely sonicated mitochondria. The NAD(+)-dependence of 3-hydroxybutyryl-CoA oxidation showed that a much smaller NAD+ concentration was enough to half-saturate the reaction in gently disrupted mitochondria than in completely disrupted ones. Thus, these observations indicate the positive kinetic consequence of organization of beta-oxidation enzymes in situ. Respiration-linked oxidation of butyryl-, octanoyl- and palmitoyl-CoA was also studied and these CoA intermediates were oxidized at approx. 50% of the rate of crotonyl- and 3-hydroxybutyryl-CoA in the gently disrupted mitochondria. In vigorously disrupted mitochondria the oxidation rate of these saturated acyl-CoA intermediates was hardly detectable indicating that the connection between the acyl-CoA dehydrogenase and the respiratory chain had been disrupted.
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PMID:Kinetic advantage of the interaction between the fatty acid beta-oxidation enzymes and the complexes of the respiratory chain. 199 30

Five distinct acyl-CoA dehydrogenases are currently known. These are short, medium, long and 2-methyl-branched-chain acyl-CoA dehydrogenases, and isovaleryl-CoA dehydrogenase. We tested these five acyl-CoA dehydrogenases for their ability to dehydrogenate valproyl-CoA using pure enzyme preparations isolated from rat liver mitochondria. The activities of the pure human short-chain, medium-chain and isovaleryl enzymes purified from post-mortem livers, and a long-chain acyl-CoA dehydrogenase preparation partially purified from placental mitochondria, were also tested. Valproyl-CoA was dehydrogenated at a significant rate (0.167 mumol/min per mg protein) only by rat 2-methyl-branched-chain acyl-CoA dehydrogenase. Human 2-methyl-branched-chain acyl-CoA dehydrogenase has not been purified; therefore, it could not be tested. Since four other human acyl-CoA dehydrogenases did not dehydrogenate isobutyryl-CoA, 2-methylbutyryl-CoA (obligatory intermediates from valine and isoleucine, respectively) nor valproyl-CoA, it is reasonable to assume that valproyl-CoA is dehydrogenated by 2-methyl-branch-chain acyl-CoA dehydrogenase in man as well. We identified 2-propyl-2-pentenoyl-CoA as the reaction product from valproyl-CoA by mass spectral analysis of the acyl moiety. Valproyl-CoA, at 0.3 mM, moderately inhibited human acyl-CoA dehydrogenases with the exception of the long-chain enzyme. 5 mM free valproic acid inhibited the activities of various acyl-CoA dehydrogenases only very weakly.
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PMID:The enzymatic basis for the metabolism and inhibitory effects of valproic acid: dehydrogenation of valproyl-CoA by 2-methyl-branched-chain acyl-CoA dehydrogenase. 211 56

Medium-chain acyl-CoA dehydrogenase reduced with octanoyl-CoA is reoxidized in two one-electron steps by two molecules of the physiological oxidant, electron transferring flavoprotein (ETF). The organometallic oxidant ferricenium hexafluorophosphate (Fc+PF6-) is an excellent alternative oxidant of the dehydrogenase and mimics a number of the features shown by ETF. Reoxidation of octanoyl-CoA-reduced enzyme (200 microM Fc+PF6- in 100 mM Hepes buffer, pH 7.6, 1 degree C) occurs in two one-electron steps with pseudo-first-order rate constants of 40 s-1 and about 200 s-1 for k1 and k2, respectively. The reaction is comparatively insensitive to ionic strength, and evidence of rate saturation is encountered at high ferricenium ion concentration. As observed with ETF, the free two-electron-reduced dehydrogenase is a much poorer kinetic reductant of Fc+PF6-, with rate constants of 3 s-1 and 0.3 s-1 (for k1 and k2, respectively) using 200 microM Fc+PF6-. In addition to the enoyl-CoA product formed during the dehydrogenation of octanoyl-CoA, binding a number of redox-inert acyl-CoA analogues (notably 3-thia- and 3-oxaoctanoyl-CoA) significantly accelerates electron transfer from the dehydrogenase to Fc+PF6-. Those ligands most effective at accelerating electron transfer favor deprotonation of reduced flavin species in the acyl-CoA dehydrogenase. Thus this rate enhancement may reflect the anticipated kinetic superiority of anionic flavin forms as reductants in outer-sphere electron-transfer processes. Evidence consistent with the presence of two distinct loci for redox communication with the bound flavin in the acyl-CoA dehydrogenase is presented.
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PMID:Alternate electron acceptors for medium-chain acyl-CoA dehydrogenase: use of ferricenium salts. 227 71

Inactivation of five distinct acyl-CoA dehydrogenases by (methylenecyclopropyl)acetyl-CoA (MCPA-CoA), the toxic metabolite of hypoglycin from unripe ackee fruit, was investigated using purified enzyme preparations. Short-chain acyl-CoA (SCADH), medium-chain acyl-CoA (MCADH) and isovaleryl-CoA (IVDH) dehydrogenases were severely and irreversibly inactivated by MCPA-CoA, while 2-methyl-branched chain acyl-CoA dehydrogenase (2-meBCADH) was only slowly and mildly inactivated. Long-chain acyl-CoA dehydrogenase (LCADH) was not significantly inactivated, even after prolonged incubation with MCPA-CoA. Inactivation of SCADH, MCADH and IVDH was effectively prevented by the addition of substrate. This mode of inactivation by MCPA-CoA explains the urinary metabolite profile in hypoglycin treated-rats, which includes large amounts of metabolites from fatty acids and leucine, and relatively small amounts of those from valine and isoleucine. Spectrophotometric titration of SCADH and MCADH with MCPA-CoA, together with the protective effects of substrate, indicates that MCPA-CoA is acted upon by, and exerts in turn irreversible inactivation of, SCADH and MCADH, confirming that MCPA-CoA is a suicide inhibitor (Wenz et al. (1981) J. Biol. Chem. 256, 9809-9812). Spectrophotometric titration data of LCADH and MCPA-CoA is typical of non-reacting CoA ester.
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PMID:Selective inactivation of various acyl-CoA dehydrogenases by (methylenecyclopropyl)acetyl-CoA. 233 85

Studies of the spectral (UV/vis and resonance Raman) and electrochemical properties of the FAD-containing enzyme glutaryl-CoA dehydrogenase (GCD) from Paracoccus denitrificans reveal that the properties of the oxidized enzyme (GCDox) appear to be invariant from those properties known for other acyl-CoA dehydrogenases such as mammalian general acyl-CoA dehydrogenase (GACD) and butyryl-CoA dehydrogenase (BCD) from Megasphaera elsdenii. However, when either free or complexed GCD is reduced, its spectral and electrochemical behavior differs from that of both GACD and BCD. Free GCD does not stabilize any form of one-electron-reduced GCD, but when GCD is complexed to its inhibitor, aceto-acetyl-CoA, the enzyme stabilizes 20% of the blue neutral radical form of FAD (FADH.) upon reduction. Like GACD, when crotonyl-CoA- (CCoA) bound GCD is reduced, the red anionic form of FAD radical (FAD.-) is stabilized, and excess reduction equivalents are necessary to effect full reduction of the complex. A comproportionation reaction is proposed between fully reduced crotonyl-CoA-bound GCD (GCD2e-CCoA) and GCDox-CCoA to partially explain the stabilization of GCD-bound FAD.- by CCoA. When GCD is reduced by its optimal substrate, glutaryl-CoA, a two-electron reduction is observed with concomitant formation of a long-wavelength charge-transfer band. It is proposed that the ETF specific for GCD abstracts one electron from this charge-transfer species and this is followed by the decarboxylation of the oxidized substrate. At pH 6.4, potential values measured for free GCD and GCD bound to acetoacetyl-CoA are -0.085 and -0.129 V, respectively. Experimental evidence is given for a positive shift in the reduction potential of GCD when the enzyme is bound to a 1:1 mixture of butyryl-CoA and CCoA. However, significant GCD hydratase activity is observed, preventing quantitation of the potential shift.
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PMID:Spectral and electrochemical properties of glutaryl-CoA dehydrogenase from Paracoccus denitrificans. 234 Feb 66

Significant thermodynamic changes have been observed for general acyl-CoA dehydrogenase (GAD) upon substrate binding. Spectroelectrochemical studies of GAD and several of its substrates have revealed that these substrates are essentially isopotential for chain lengths of C-4 to C-16 (E 0' =-0.038 to -0.045 V vs SHE). When GAD is bound by these substrates, a dramatic shift in the midpoint potential of the enzyme is observed (E 0' = -0.136 V for ligand-free GAD and -0.026 V for acyl-CoA-bound GAD), thus allowing a thermodynamically favorable transfer of electrons from substrate to enzyme. This contrasts with values reported elsewhere. From these data an isopotential scheme of electron delivery into the electron-transport chain is proposed.
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PMID:Regulation of the redox potential of general acyl-CoA dehydrogenase by substrate binding. 234 Feb 67

3-Phenylpropionic acid is an end-product of the bacterial degradation of unabsorbed phenylalanine in the intestinal lumen. As CoA ester, this metabolite has been considered to be a specific substrate for medium chain acyl-CoA dehydrogenase (MCAD). Its glycine-conjugate, 3-phenylpropionylglycine, has now been established as a pathognomonic marker in urine from patients affected with MCAD deficiency. However, no systematic studies to evaluate the reactivity of 3-phenylpropionyl-CoA with other known acyl-CoA dehydrogenases have so far been carried out to establish the specificity of this substrate for MCAD. We studied the in vitro reactivity of 3-phenylpropionyl-CoA with five rat and human liver acyl-CoA dehydrogenases using purified preparations. we demonstrated that MCAD effectively dehydrogenated 3-phenylpropionyl-CoA, and that no other acyl-CoA dehydrogenase exhibited any significant activity with this substrate. In the steady state condition, the Km of 3-phenylpropionyl-CoA for human MCAD was 50 microM. Gas chromatography/mass spectrometry analysis of the assay mixture identified trans-cinnamoyl-CoA as the product of the reaction. Furthermore, we showed by determination of the reaction products using gas chromatography/mass spectrometry selected ion monitoring that, in absence of the primary electron acceptor, 3-phenylpropionyl-CoA was slowly but significantly dehydrogenated by MCAD under aerobic conditions. These data suggest that MCAD may oxidize 3-phenylpropionyl-CoA in vivo using an alternative electron acceptor, to produce trans-cinnamoyl-CoA. This mechanism provides an explanation for the normal 3-phenylpropionylglycine excretion observed in urine from patients affected with glutaric aciduria type II and ethylmalonic/adipic aciduria.
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PMID:The enzymatic basis for the dehydrogenation of 3-phenylpropionic acid: in vitro reaction of 3-phenylpropionyl-CoA with various acyl-CoA dehydrogenases. 234 78

A sensitive assay for medium chain acyl-CoA dehydrogenase has been developed by substituting ferricenium hexafluorophosphate for the physiological acceptor, electron transferring flavoprotein. The ferricenium ion is a facile oxidant of the octanoyl-CoA-reduced enzyme with a Vmax of 1400 min-1 and a KM of 55 microM at pH 7.6. The ferricenium assay does not require additional mediator dyes, exhibits low background rates, and avoids the necessity of purifying substantial amounts of electron transferring flavoprotein. Unlike the fluorescence-based electron transferring flavoprotein assay, this new procedure can be performed aerobically. Both assays give comparable results when tested with crude fibroblast homogenates from normal and medium chain acyl-CoA dehydrogenase deficient patients. The convenience of the ferricenium method suggests it may be generally useful as a screening assay for a number of acyl-CoA dehydrogenases.
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PMID:An acyl-coenzyme A dehydrogenase assay utilizing the ferricenium ion. 236

The acetylenic thioester, 2-octynoyl-CoA, inactivates medium chain acyl-CoA dehydrogenase from pig kidney by two distinct pathways depending on the redox state of the FAD prosthetic group. Inactivation of the oxidized dehydrogenase occurs with labeling of an active site glutamate residue and elimination of CoASH. Incubation of the reduced dehydrogenase with 2-octynoyl-CoA rapidly forms a kinetically stable dihydroflavin species which is resistant to reoxidation using trans-2-octenoyl-CoA, molecular oxygen, or electron transferring flavoprotein. The reduced enzyme derivative shows extensive bleaching at 446 nm with shoulders at 320 and 380 nm. Denaturation of the reduced derivative in 80% methanol yields a mixture of products which was characterized by HPLC, by uv/vis, and by radiolabeling experiments. Approximately 20% of the flavin is recovered as oxidized FAD, about 40% is retained covalently attached to the protein, and the remainder is distributed between several species eluting after FAD on reverse-phase HPLC. The spectrum of one of these species ressembles that of a N(5)-C(4a) dihydroflavin adduct. These data suggest that a primary reduced flavin species undergoes various rearrangements during release from the protein. The possibility that the inactive modified enzyme represents a covalent adduct between 2-octynoyl-CoA and reduced flavin is discussed. Analogous experiments using enzyme substituted with 1,5-dihydro-5-deaza-FAD show rapid and quantitative reoxidation of the flavin by 0.5 eq of 2-octynoyl-CoA.
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PMID:Inactivation of two-electron reduced medium chain acyl-CoA dehydrogenase by 2-octynoyl-CoA. 256 47


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