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:1.3.99.3 (acyl-CoA dehydrogenase)
1,425 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Freeze-thawed rat liver mitochondria were extensively washed with potassium phosphate, pH 7.5, and the residue was extracted with 10 mM potassium phosphate, pH 7.5, 1% (w/v) sodium cholate, 0.5 M KCl. The four beta-oxidation enzyme activities of the washes and the last extract were assayed with substrates of various carbon chain lengths. Our data suggest that the last extract contains a novel acyl-CoA dehydrogenase and long-chain 3-hydroxyacyl-CoA dehydrogenase. A novel acyl-CoA dehydrogenase was purified. The molecular masses of the native enzyme and the subunit were estimated to be 150 and 71 kDa, respectively. One mole of enzyme contained 2 mole of FAD. These properties and immunochemical properties of the enzyme differed from those of three other acyl-CoA dehydrogenases: short-, medium-, and long-chain acyl-CoA dehydrogenases. Carbon chain length specificity of the enzyme differed from that of other acyl-CoA dehydrogenases. The enzyme was active toward CoA esters of long- and very-long-chain fatty acids, but not toward those of medium- and short-chain fatty acids. The specific enzyme activity was greater than 10 times that of long-chain acyl-CoA dehydrogenase when palmitoyl-CoA was used as substrate. We propose the name "very-long-chain acyl-CoA dehydrogenase" for this enzyme.
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PMID:Novel fatty acid beta-oxidation enzymes in rat liver mitochondria. I. Purification and properties of very-long-chain acyl-coenzyme A dehydrogenase. 173 Jun 32

We have used radio-high pressure liquid chromatography to study the acyl-CoA ester intermediates and the acylcarnitines formed during mitochondrial fatty acid oxidation. During oxidation of [U-14C]hexadecanoate by normal human fibroblast mitochondria, only the saturated acyl-CoA and acylcarnitine esters can be detected, supporting the concept that the acyl-CoA dehydrogenase step is rate-limiting in mitochondrial beta-oxidation. Incubations of fibroblast mitochondria from patients with defects of beta-oxidation show an entirely different profile of intermediates. Mitochondria from patients with defects in electron transfer flavoprotein and electron transfer flavoprotein:ubiquinone oxido-reductase are associated with slow flux through beta-oxidation and accumulation of long chain acyl-CoA and acylcarnitine esters. Increased amounts of saturated medium chain acyl-CoA and acylcarnitine esters are detected in the incubations of mitochondria with medium chain acyl-CoA dehydrogenase deficiency, whereas long chain 3-hydroxyacyl-CoA dehydrogenase deficiency is associated with accumulation of long chain 3-hydroxyacyl- and 2-enoyl-CoA and carnitine esters. These studies show that the control strength at the site of the defective enzyme has increased. Radio-high pressure liquid chromatography analysis of intermediates of mitochondrial fatty acid oxidation is an important new technique to study the control, organization and defects of the enzymes of beta-oxidation.
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PMID:Quantitation of acyl-CoA and acylcarnitine esters accumulated during abnormal mitochondrial fatty acid oxidation. 174 86

In summary, the vitamin pantothenic acid is an integral part of the acylation carriers, CoA and acyl carrier protein (ACP). The vitamin is readily available from diverse dietary sources, a fact which is underscored by the difficulty encountered in attempting to induce pantothenate deficiency. Although pantothenic acid deficiency has not been linked with any particular disease, deficiency of the vitamin results in generalized malaise clinically. In view of the fact that pantothenate is required for the synthesis of CoA, it is surprising that tissue CoA levels are not altered in pantothenate deficiency. This suggests that the cell is equipped to conserve its pantothenate content, possibly by a recycling mechanism for utilizing pantothenate obtained from degradation of pantothenate-containing molecules. Although the steps involved in the conversion of pantothenate to CoA have been characterized, much remains to be done to understand the regulation of CoA synthesis. In particular, in view of what is known about the in vitro regulation of pantothenate kinase, it is surprising that the enzyme is active in vivo, since factors that are known to inhibit the enzyme are present in excess of the concentrations known to inhibit the enzyme. Thus, other physiological regulatory factors (which are largely unknown) must counteract the effects of these inhibitors, since the pantothenate-to-CoA conversion is operative in vivo. Another step in the biosynthetic pathway that may be rate limiting is the conversion of 4'-phosphopantetheine (4'-PP) to dephospho-CoA, a step catalyzed by 4'-phosphopantetheine adenylyl-transferase. In mammalian systems, this step may occur in the mitochondria or in the cytosol. The teleological significance of these two pathways remains to be established, particularly since mitochondria are capable of transporting CoA from the cytosol. Altered homeostasis of CoA has been observed in diverse disease states including starvation, diabetes, alcoholism, Reye syndrome (RS), medium-chain acyl CoA dehydrogenase deficiency, vitamin B12 deficiency, and certain tumors. Hormones, such as glucocorticoids, insulin, and glucagon, as well as drugs, such as clofibrate, also affect tissue CoA levels. It is not known whether the abnormal metabolism observed in these conditions is the result of altered CoA metabolism or whether CoA levels change in response to hormonal or nonhormonal perturbations brought about in these conditions. In other words, a cause-effect relation remains to be elucidated. It is also not known whether the altered CoA metabolism (be it cause or result of abnormal metabolism) can be implicated in the manifestations of a disease. Besides CoA, pantothenic acid is also an integral part of the ACP molecule.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Pantothenic acid in health and disease. 174 61

A patient with riboflavin-responsive mild multiple acyl-CoA dehydrogenation deficiency of the ethylmalonic--adipic aciduria type experienced a recurrence of spontaneous hypoglycaemic episodes whilst being given supplementary L-carnitine. This phenomenon is explicable in terms of the known biochemical features of this condition and suggests caution in the carnitine supplementation of patients with defective oxidation of medium- or short-chain fatty acyl-CoA esters. This patient excreted excessive phenylpropionylglycine after an oral phenylpropionic acid load. Thus the phenylpropionic acid loading test is not completely specific for primary medium-chain acyl-CoA dehydrogenase deficiency as has been supposed.
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PMID:Possible deleterious effect of L-carnitine supplementation in a patient with mild multiple acyl-CoA dehydrogenation deficiency (ethylmalonic-adipic aciduria). 177 16

A trifunctional beta-oxidation protein, designated TFP, was purified to apparent homogeneity from oleate-induced mycelia of Neurospora crassa. 2-Enoyl-CoA hydratase, L-3-hydroxyacyl-CoA dehydrogenase, and 3-hydroxyacyl-CoA epimerase activities copurified in constant ratios with this protein when crude extracts were subjected to cation-exchange, dye-ligand, and adsorption chromatography. Trifunctionality was substantiated by coinciding enzyme activity ratios during the last two purification steps and additional chromatographic steps. The enzyme was shown to be a 365-kDa tetramer of subunits with a molecular mass of 93 kDa. Several lines of evidence suggest that these subunits are identical. Monospecific antibodies raised against the homogenous protein specifically precipitated the three enzymatic activities of TFP. Immunoblotting of fractions obtained after sucrose density gradient centrifugation of a crude extract indicated that TFP was exclusively localized in glyoxysome-like microbodies. The beta-oxidation system of N. crassa is structurally related to those of peroxisomes despite the presence of an acyl-CoA dehydrogenase rather than an acyl-CoA oxidase. A mitochondrial 2-enoyl-CoA hydratase activity was separated from TFP and purified to apparent homogeneity. The absence of all other beta-oxidation activities from mitochondria suggests that this organelle and its 2-enoyl-CoA hydratase are not involved in fatty acid degradation in N. crassa.
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PMID:The beta-oxidation system in catalase-free microbodies of the filamentous fungus Neurospora crassa. Purification of a multifunctional protein possessing 2-enoyl-CoA hydratase, L-3-hydroxyacyl-CoA dehydrogenase, and 3-hydroxyacyl-CoA epimerase activities. 183 48

The free two-electron-reduced form of medium-chain acyl-CoA dehydrogenase is reoxidized by 120 microM molecular oxygen (50 mM phosphate buffer, pH 7.6, 2 degrees C) with a half-time of approximately 7 s. Reoxidation yields hydrogen peroxide as a major product with only traces of the superoxide anion. In contrast, enzyme reduced with octanoyl-CoA is extremely slowly reoxidized oxygen, and so a series of 14 different substrate analogues have been tested to assess the structural factors responsible for this effect. Complexes with redox-inactive ligands such as 3-thia- and 2-azaoctanoyl-CoA lead to an approximately 3000-fold slowing of the rate of reoxidation of the free dihydroflavin form of the enzyme. Comparable ligands lacking the thioester carbonyl function are much less effective with rates some 1.3-4-fold slower than the free enzyme. The strong suppression of oxygen reactivity observed with certain ligands is probably not simply a steric effect but may reflect desolvation of the active site and consequent destabilization of the superoxide anion intermediate formed during reoxidation of the flavin. The profound differences in oxygen reactivity between acyl-CoA dehydrogenase and acyl-CoA oxidase and the unusual stability of certain flavoprotein semiquinones in air are discussed in terms of these thermodynamic and kinetic arguments.
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PMID:Reactivity of medium-chain acyl-CoA dehydrogenase toward molecular oxygen. 186 64

Dicarboxylic aciduria occurs during increased mobilization or inhibited beta-oxidation of fatty acids. In these conditions, a number of 3-hydroxydicarboxylic acids are excreted in the urine. These 3-hydroxydicarboxylic acids include 3-hydroxyadipic (3OHDC6), 3-hydroxyoctanedioic (3OHDC8), 3-hydroxydecanedioic (3OHDC10), 3-hydroxydodecanedioic (3OHDC12), and a number of unsaturated homologues. The metabolic origin of these 3-hydroxydicarboxylic acids is from the omega-oxidation of 3-hydroxy fatty acids. Subsequent beta-oxidation of the dicarboxylates yields lower-chain 3-hydroxydicarboxylic acids. A new defect in fatty acid oxidation characterized by increased urinary ratios of 3OHDC6, 3OHDC12, and unsaturated 3OHDC14s relative to 3OHDC10 is described. This pattern is consistent with a defect in long-chain 3-hydroxyacyl-CoA dehydrogenase (LHAD), which was confirmed by enzyme assay in fibroblasts. In contrast, patients with medium-chain acyl-CoA dehydrogenase (MCAD) deficiency had lower ratios of 3OHDC6 and 3OHDC8 to 3OHDC10, consistent with a decreased activity of MCAD. Nonketotic dicarboxylic aciduria, other than MCAD and LHAD deficiencies, is shown to have a normal 3-hydroxydicarboxylic acid profile when compared with fasting normal controls. Since increased excretion of 3-hydroxydicarboxylic acids was observed in all patients with dicarboxylic aciduria, an increased excretion of these compounds is not an adequate criterion to suspect a defect in 3-hydroxyacyl-CoA dehydrogenases. The analysis of the metabolite ratios (3OHDC6 and 3OHDC12 relative to 3OHDC10) is a more useful indicator for defects in LHAD.
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PMID:Urinary 3-hydroxydicarboxylic acids in pathophysiology of metabolic disorders with dicarboxylic aciduria. 187 Apr 21

Studies on fatty acid oxidation were made in rats fed for 6 months on a liquid diet containing 15% total calories as ethanol. After 6 months, a marked diminution was observed in the in vivo production of 14CO2 from labeled palmitate and octanoate in the ethanol-fed animals compared to their pair-fed isocaloric controls not receiving alcohol. Similar results were obtained in 14CO2 formation from 14C-fatty acids using liver mitochondria from these ethanol-fed rats after 6 months. The effect on octanoate beta-oxidation was larger than that for palmitate. Addition of purified acyl CoA dehydrogenase complexes and additional electron transfer flavoprotein complex to the mitochondria suggested that the ethanol-fed animals could have been deficient in the medium-chain acyl CoA-dehydrogenase complex.
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PMID:A probable defect in the beta-oxidation of lipids in rats fed alcohol for 6 months. 190 48

To study the structure-activity relationship between pentanoic acid analogues and the inhibition of fatty acid oxidation, a number of 4-pentenoic and methylenecyclopropaneacetic acid derivatives were prepared. All compounds inhibited palmitoylcarnitine oxidation in rat liver mitochondria, with 50% inhibition occurring at a concentration between 6 and 100 microM. However, only methylenecyclopropaneacetic acid (MCPA) and spiropentaneacetic acid (SPA) showed in vivo inhibitory activity in rats as indicated by the occurrence of dicarboxylic aciduria. Rats treated with SPA excreted metabolites derived only from fatty acid oxidation whereas MCPA-treated rats also excreted metabolites derived from branch-chained amino acid and lysine metabolism. SPA is a specific inhibitor of fatty acid oxidation without affecting amino acid metabolism. The site of inhibition is medium-chain acyl-CoA dehydrogenase (MCAD). In contrast, MCPA inhibited both MCAD and short-chain acyl-CoA dehydrogenase with a stronger inhibition toward the latter. The inhibition of fatty acid oxidation by both inhibitors was partially reversible by glycine or l-carnitine. Since SPA does not form a ring-opened nucleophile such as that proposed for MCPA in the inhibition of FAD prosthetic group in acyl-CoA dehydrogenases, we propose that the irreversible inhibition by SPA occurs by a tight complex without forming a covalent bond to the isoalloxazine ring in FAD.
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PMID:Spiropentaneacetic acid as a specific inhibitor of medium-chain acyl-CoA dehydrogenase. 193 95

The cDNA of human medium chain acyl-CoA dehydrogenase (MCADH) was modified by in vitro mutagenesis, and the sequence encoding the mature form of MCADH was introduced into an inducible expression plasmid. We observed synthesis of the protein in Escherichia coli cells transformed with this plasmid with measurable MCADH enzyme activity in cell extracts. Glutamic acid 376, which has been proposed by Powell and Thorpe (Powell, P. J., and Thorpe, J. (1988) Biochemistry 27, 8022-8028) as an essential residue and the proton-abstracting base at the active site of the enzyme, was mutated to glutamine. After expression in bacteria of this plasmid, the corresponding extracts show no detectable MCADH activity, although mutant MCADH-protein production was detected by protein immunoblots. The mature enzyme and the Gln376 mutant were purified to apparent homogeneity. The wild-type enzyme is a yellow protein due to the content of stoichiometric FAD and had a specific activity which is 50% of MCADH purified from pig kidney. The Gln376 mutant is devoid of activity (less than 0.02% that of wild type, expressed enzyme) and is green because of bound CoA persulfide. Properties of the mutant enzyme suggest that the Glu376----Gln change specifically affects substrate binding. These results prove that Glu376 plays an important role in the initial step of dehydrogenation catalysis.
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PMID:Characterization of wild-type and an active site mutant of human medium chain acyl-CoA dehydrogenase after expression in Escherichia coli. 197 May 66


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