Linked Life Data

10985795

Source:http://linkedlifedata.com/resource/pubmed/id/10985795

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
37
pubmed:dateCreated
2000-10-19
pubmed:abstractText
Glutaryl-CoA dehydrogenase catalyzes the oxidation of glutaryl-CoA to crotonyl-CoA and CO(2) in the mitochondrial degradation of lysine, hydroxylysine, and tryptophan. We have characterized the human enzyme that was expressed in Escherichia coli. Anaerobic reduction of the enzyme with sodium dithionite or substrate yields no detectable semiquinone; however, like other acyl-CoA dehydrogenases, the human enzyme stabilizes an anionic semiquinone upon reduction of the complex between the enzyme and 2,3-enoyl-CoA product. The flavin potential of the free enzyme determined by the xanthine-xanthine oxidase method is -0.132 V at pH 7.0, slightly more negative than that of related flavoprotein dehydrogenases. A single equivalent of substrate reduces 26% of the dehydrogenase flavin, suggesting that the redox equilibrium on the enzyme between substrate and product and oxidized and reduced flavin is not as favorable as that observed with other acyl-CoA dehydrogenases. This equilibrium is, however, similar to that observed in isovaleryl-CoA dehydrogenase. Comparison of steady-state kinetic constants of glutaryl-CoA dehydrogenase with glutaryl-CoA and the alternative substrates, pentanoyl-CoA and hexanoyl-CoA, suggests that the gamma-carboxyl group of glutaryl-CoA stabilizes the enzyme-substrate complex by at least 5.7 kJ/mol, perhaps by interaction with Arg94 or Ser98. Glu370 is positioned to function as the catalytic base, and previous studies indicate that the conjugate acid of Glu370 also protonates the transient crotonyl-CoA anion following decarboxylation [Gomes, B., Fendrich, G. , and Abeles, R. H. (1981) Biochemistry 20, 3154-3160]. Glu370Asp and Glu370Gln mutants of glutaryl-CoA dehydrogenase exhibit 7% and 0. 04% residual activity, respectively, with human electron-transfer flavoprotein; these mutations do not grossly affect the flavin redox potentials of the mutant enzymes. The reduced catalytic activities of these mutants can be attributed to reduced extent and rate of substrate deprotonation based on experiments with the nonoxidizable substrate analogue, 3-thiaglutaryl-CoA, and kinetic experiments. Determination of these fundamental properties of the human enzyme will serve as the basis for future studies of the decarboxylation reaction which is unique among the acyl-CoA dehydrogenases.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
19
pubmed:volume
39
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
11488-99
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed-meshheading:10985795-Acyl Coenzyme A, pubmed-meshheading:10985795-Amino Acid Substitution, pubmed-meshheading:10985795-Binding Sites, pubmed-meshheading:10985795-Electron Transport, pubmed-meshheading:10985795-Glutamic Acid, pubmed-meshheading:10985795-Glutaryl-CoA Dehydrogenase, pubmed-meshheading:10985795-Humans, pubmed-meshheading:10985795-Kinetics, pubmed-meshheading:10985795-Mutagenesis, Site-Directed, pubmed-meshheading:10985795-Oxidation-Reduction, pubmed-meshheading:10985795-Oxidoreductases, pubmed-meshheading:10985795-Oxidoreductases Acting on CH-CH Group Donors, pubmed-meshheading:10985795-Protons, pubmed-meshheading:10985795-Recombinant Proteins, pubmed-meshheading:10985795-Spectrophotometry, pubmed-meshheading:10985795-Substrate Specificity, pubmed-meshheading:10985795-Titrimetry
pubmed:year
2000
pubmed:articleTitle
Proton abstraction reaction, steady-state kinetics, and oxidation-reduction potential of human glutaryl-CoA dehydrogenase.
pubmed:affiliation
Departments of Pediatrics and Pharmaceutical Sciences, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't