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)

1. State-3 (i.e. ADP-stimulated) rates of O(2) uptake with palmitoylcarnitine, palmitoyl-CoA plus carnitine, pyruvate plus malonate plus carnitine and octanoate as respiratory substrate were all diminished in heart mitochondria isolated from senescent (24-month-old) rats compared with mitochondria from young adults (6 months old). By contrast, State-3 rates of O(2) uptake with pyruvate plus malate or glutamate plus malate were the same for mitochondria from each age group. 2. Measurements of enzyme activities in disrupted mitochondria showed a decline with senescence in the activity of acyl-CoA synthetase (EC 6.2.1.2 and 6.2.1.3), carnitine acetyltransferase (EC 2.3.1.7) and 3-hydroxy-acyl-CoA dehydrogenase (EC 1.1.1.35), but no change in the activity of carnitine palmitoyltransferase (EC 2.3.1.21) or acyl-CoA dehydrogenase (EC 1.3.99.3). 3. Measurement of dl-[(3)H]carnitine (in)/acetyl-l-carnitine (out) exchange in intact mitochondria showed decreased rates when the animals used were senescent. However, this followed from a decreased intramitochondrial pool of exchangeable carnitine, such that calculated first-order rate constants for exchange were identical in mitochondria from the two age groups. 4. The decline in acyl-CoA synthetase activity is thought to be the reason for the diminished rate of O(2) uptake with octanoate in senescence. The decline in carnitine acetyltransferase activity is considered to be the cause of the diminished rate of O(2) uptake with acetylcarnitine or with pyruvate plus malonate plus carnitine as substrate. The mechanism of the diminished rate of O(2) uptake with palmitoylcarnitine in senescence is discussed.
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PMID:Lipid oxidation by heart mitochondria from young adult and senescent rats. 63 43

Medium chain acyl-CoA dehydrogenase (MCAD) catalyzes the first reaction of the beta-oxidation cycle for 4-10-carbon fatty acids. MCAD deficiency is one of the most frequent inborn metabolic disorders in populations of northwestern European origin. In the compilation of data from a worldwide study of 172 unrelated patients each representing an independent pedigree, a total of 8 different mutations have been identified. Among them, a single prevalent mutation, 985A-->G, was found in 90% of 344 variant alleles. 985A-->G causes glutamate substitution for lysine-304 in the mature MCAD subunit, which causes impairment of tetramer assembly and instability of the protein. Three of 7 rarer mutations have been identified in a few unrelated patients, while the remaining 4 have each been found in only a single pedigree. In addition to tabulating the mutations, the acyl-CoA dehydrogenase gene family, the structure of the MCAD gene and the evolution of 985A-->G mutation are briefly discussed.
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PMID:Mutations in the medium chain acyl-CoA dehydrogenase (MCAD) gene. 136 5

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

Rats treated with six to eight doses (80 mg/kg, i.p.) of 4-pentenoic acid, an inhibitor of mitochondrial fatty acid oxidation in vitro, during a 48-hr starvation period developed microvesicular fatty infiltration of the liver similar to that observed in Reye's Syndrome. Hepatic triglycerides were elevated an average of 5-fold, although considerable variability was found between individual rats. Fed rats did not develop fatty liver upon similar treatment with pentenoic acid. Liver mitochondria isolated from rats with pentenoic acid-induced fatty liver showed a persistent inhibition of fatty acid oxidation. Rates of oxidation of palmitoylcarnitine and decanoylcarnitine were decreased about 70%, while that of octanoylcarnitine was decreased 50%. Carnitine-independent oxidation of octanoate was also inhibited. Oxidation rates for substrates other than fatty acids, including glutamate, succinate, pyruvate, and alpha-ketoglutarate, were unaffected. Measurements of flavoprotein reduction in intact mitochondria indicated that neither palmitoylcarnitine nor palmitoyl CoA plus L-carnitine could elicit reduction of acyl-CoA dehydrogenase and electron transferring flavoprotein in mitochondria from rats with pentenoic acid-induced fatty liver. These results support a site of inhibition of mitochondrial beta-oxidation at the level of acyl-CoA dehydrogenase for pentenoic acid treatment in vivo, and they suggest a role for nutritional or hormonal factors in the metabolic disposition of pentenoic acid in vivo and in the development of fatty liver.
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PMID:Inhibition of mitochondrial fatty acid oxidation in pentenoic acid-induced fatty liver. A possible model for Reye's syndrome. 671 30

2-Pentynoyl-CoA is a mechanism-based inactivator of the flavoprotein short-chain acyl-CoA dehydrogenase from pig liver. Inactivation is associated with the formation of an intermediate absorbing at 800 nm and results in the incorporation of 0.86 +/- 0.13 molecules of radiolabeled inhibitor per subunit. A rapid procedure was devised to isolate the labeled peptide. A glutamate residue was identified as the target of 2-pentynoyl-CoA treatment and proved homologous to the proposed catalytic base, GLU376, in the corresponding medium-chain acyl-CoA dehydrogenase sequence. These results are discussed in terms of the lack of conservation of this glutamate residue in the acyl-CoA dehydrogenase enzyme family.
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PMID:Inactivation of short-chain acyl-coenzyme A dehydrogenase from pig liver by 2-pentynoyl-coenzyme A. 837 83

The catalytically essential glutamate residue that initiates catalysis by abstracting the substrate alpha-hydrogen as H+ is located at position 376 (mature MCADH numbering) on loop JK in medium chain acyl-CoA dehydrogenase (MCADH). In long chain acyl-CoA dehydrogenase (LCADH) and isovaleryl-CoA dehydrogenase (IVDH), the corresponding Glu carrying out the same function is placed at position 255 on the adjacent helix G. These glutamates thus act on substrate approaching from two opposite regions at the active center. We have implemented the topology of LCADH in MCADH by carrying out the two mutations Glu376Gly and Thr255Glu. The resulting chimeric enzyme, "medium-/long" chain acyl-CoA dehydrogenase (MLCADH) has approximately 20% of the activity of MCADH and approximately 25% that of LCADH with its best substrates octanoyl-CoA and dodecanoyl-CoA, respectively. MLCADH exhibits an enhanced rate of reoxidation with oxygen, however, with a much narrower substrate chain length specificity that peaks with dodecanoyl-CoA. This is the same maximum as that of LCADH and is thus significantly shifted from that of native MCADH (hexanoyl/octanoyl-CoA). The putative, common ancestor of LCADH and IVDH has two Glu residues, one each at positions 255 and 376. The corresponding MCADH mutant, Thr255Glu (glu/glu-MCADH), is as active as MCADH with octanoyl-CoA; its activity/chain length profile is, however, much narrower. The topology of the Glu as H+ abstracting base seems an important factor in determining chain length specificity and reactivity in acyl-CoA dehydrogenases. The mechanisms underlying these effects are discussed in view of the three-dimensional structure of MLCADH, which is presented in the accompanying paper [Lee et al. (1996) Biochemistry 35, 12412-12420].
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PMID:Medium-long-chain chimeric human Acyl-CoA dehydrogenase: medium-chain enzyme with the active center base arrangement of long-chain Acyl-CoA dehydrogenase. 882 75

The acyl-CoA dehydrogenases are a family of flavoenzymes with similar structure and function involved in the metabolism of fatty acids and branched chain amino acids. The degree of overlap in substrate specificity is narrow among these enzymes. The position of the catalytic glutamate, identified as Glu376 in porcine medium chain acyl-CoA dehydrogenase (MCAD), Glu254 in human isovaleryl-CoA dehydrogenase (IVD), and Glu261 in human long chain acyl-CoA dehydrogenase (LCAD), has been suggested to affect substrate chain length specificity. In this study, in vitro site-directed mutagenesis was used to investigate the effect of changing the position of the catalytic carboxylate on substrate specificity in short chain acyl-CoA dehydrogenase (SCAD). Glu368, the hypothetical active site catalytic residue of rat SCAD, was replaced with Asp, Gly, Gln, Arg, and Lys and the wild type and mutant SCADs were produced in Escherichia coli and purified. The recombinant wild type SCAD kcat/K(m) values for butyryl-hexanoyl-, and octanoyl-CoA were 220, 22, and 3.2 microM-1 min-1, respectively, while the Glu368Asp mutant gave kcat/K(m) of 81, 12, and 1.4 microM-1 min-1, respectively, for the same substrates. None of the other mutants exhibited enzyme activity. A Glu368Gly/Gly247Glu double mutant enzyme, which places the catalytic residue at a position homologous to that of LCAD, was also synthesized and purified. It showed kcat/K(m) of 9.3, 2.8, and 1.5 microM-1 min-1 with butyryl-, hexanoyl-, and octanoyl-CoA used as substrates, respectively. These results confirm the identity of Glu368 as the catalytic residue of rat SCAD and suggest that alteration of the position of the catalytic carboxylate can modify substrate specificity.
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PMID:Functional role of the active site glutamate-368 in rat short chain acyl-CoA dehydrogenase. 895 87

The catalytically essential glutamate base in the acyl-CoA dehydrogenase family is found either on the loop between J and K helices (e.g., in short-chain, medium-chain, and glutaryl-CoA dehydrogenases) or on the G helix (long-chain and isovaleryl-CoA dehydrogenases). While active-site bases at either position are functionally equivalent with respect to alpha-proton abstraction, reactions that require removal of a gamma-proton show marked differences between the two enzyme classes. Thus short-chain, medium-chain, and glutaryl-CoA dehydrogenase are rapidly inactivated by 2-pentynoyl-CoA with abstraction of a gamma-proton, whereas isovaleryl-CoA dehydrogenase is not significantly inhibited. This resistance is not due to weak binding: the complex between isovaleryl-CoA dehydrogenase and 2-pentynoyl-CoA shows a Kd of 1.8 microM at pH 7.6. Migration of the catalytic base to the loop between J and K helices (using the Glu254Gly/Ala375Glu double mutant) makes isovaleryl-CoA dehydrogenase sensitive to irreversible inhibition by 2-pentynoyl-CoA. Molecular modeling suggests that this mutation brings the catalytic base close enough to abstract a gamma-proton from the bound inhibitor. Experiments with two mechanism-based inactivators that target the FAD of the medium- and short-chain acyl-CoA dehydrogenases support this conclusion. 3-Methyl-3-butenoyl-CoA requires activation by alpha-proton abstraction and rapidly yields a reduced flavin adduct with wild-type isovaleryl-CoA dehydrogenase. In contrast, the isomeric 3-methyl-2-butenoyl-CoA is inert toward this enzyme because it cannot be activated by gamma-proton abstraction. Molecular modeling supports these observations. This unusual selectivity toward mechanism-based inactivators provides additional discrimination between members of the acyl-CoA dehydrogenase family.
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PMID:Mechanism-based inhibitor discrimination in the acyl-CoA dehydrogenases. 920 18

Medium chain acyl-CoA dehydrogenase (MCAD) is a tetrameric flavoprotein essential for the beta-oxidation of medium chain fatty acids. MCAD deficiency (MCADD) is an inherited error of fatty acid metabolism. The gene for MCAD is located on chromosome one (1p31). One variant of the MCAD gene, G985A, a point mutation causing a change from lysine to glutamate at position 304 (K304E) in the mature MCAD protein, has been found in 90% of the alleles in MCADD patients identified retrospectively. There is a high frequency of MCADD among people of Northern European descent, which is believed to be due to a founder effect. MCADD is inherited in an autosomal recessive manner. Of patients clinically diagnosed with MCADD, 81% who have been identified retrospectively are homozygous for K304E, and 18% are compound heterozygotes for K304E. Clinical data on the probability of clinical disease indicates that MCADD patients are at risk for the following outcomes: hypoglycemia, vomiting, lethargy, encephalopathy, respiratory arrest, hepatomegaly, seizures, apnea, cardiac arrest, coma, and sudden and unexpected death. Long-term outcomes include developmental and behavioral disability, chronic muscle weakness, failure to thrive, cerebral palsy, and attention deficit disorder (ADD). Differences in clinical disease specific to allelic variants have not been documented. Factors that may increase risk for disease onset or modify disease severity are age when the first episode occurred, fasting, and presence of infection. Acute attacks must be treated immediately with appropriate intravenous doses of glucose. For those diagnosed, long-term management of the disease includes preventing stress caused by fasting and maintaining a high-carbohydrate, reduced-fat diet, and carnitine supplementation. Hospitalization costs attributable to morbidity and mortality from MCADD are unknown; MCADD is not a diagnosis in the International Classification of Disease, 10th Revision (ICD-10) codebook. Furthermore, the penetrance of the MCAD genotypes is unknown; there appears to be a substantial number of asymptomatic MCADD individuals and some uncertainty regarding which individuals will manifest symptoms and which individuals will remain asymptomatic. Several technologies are available to detect MCADD. Diagnostic technologies include DNA-based tests for K304E mutations using the polymerase chain reaction (PCR), and the detection of abnormal metabolites in urine. Screening technologies include tandem mass spectrometry (MS/MS), which detects abnormal metabolites mostly in blood. State programs are beginning to offer screening in newborns for MCADD using MS/MS. In addition, a private company currently offers voluntary supplemental newborn screening for MCADD to birthing centers.
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PMID:Medium chain acyl-CoA dehydrogenase deficiency human genome epidemiology review. 1126 45

The flavoenzyme nitroalkane oxidase catalyzes the oxidation of primary and secondary nitroalkanes to the respective aldehydes or ketones, releasing nitrite. The enzyme has recently been identified as being homologous to the acyl-CoA dehydrogenase family of enzymes [Daubner, S. C., Gadda, G., Valley, M. P., and Fitzpatrick, P. F. (2002) Proc. Natl. Acad. Sci. U.S.A. 99, 2702-2707]. The glutamate which acts as an active site base in that family of enzymes aligns with Asp402 of nitroalkane oxidase. To evaluate the identification of Asp402 as an active site base, the effect of mutation of Asp402 to glutamate on the rate of cleavage of the nitroalkane C-H bond has been determined. Deuterium kinetic isotope effects on steady state kinetic parameters and direct measurement of the rate of flavin reduction establish that the mutation increases the DeltaG(++) for C-H bond cleavage by 1.6-1.9 kcal/mol. There is no effect on the rate of reaction of the reduced enzyme with oxygen. These results support the assignment of Asp402 as the active site base in nitroalkane oxidase.
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PMID:Reductive half-reaction of nitroalkane oxidase: effect of mutation of the active site aspartate to glutamate. 1274 43


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