Linked Life Data

7696316

Source:http://linkedlifedata.com/resource/pubmed/id/7696316

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1995-5-2
pubmed:abstractText
The pH dependence of avian cytosolic HMG-CoA synthase activity is fit by a titration curve with a pK = 8.6. The observation of optimal activity at alkaline pH and the insensitivity of pK to divalent cation concentration suggest that the pK reflects ionization of an amino-acid side chain (e.g., cysteinyl sulfhydryl) rather than substrate enolization. Upon reaction of 3-chloropropionyl-CoA with HMG-CoA synthase C129S, an enzyme variant lacking the sulfhydryl group normally targeted by this mechanism-based inhibitor, stoichiometric modification occurs. Amino-acid analysis indicates that cysteine is the principal target in C129S enzyme, demonstrating the presence of a second reactive cysteine within this enzyme. To test whether another cysteine functions in reaction chemistry, conserved cysteines were identified by sequence homology analysis. Five cysteine residues (C59, C69, C224, C232, C268), invariant in the nine sequences available for various eukaryotic HMG-CoA synthase isozymes, were individually replaced by alanine in a series of mutant enzymes. Kinetic analyses of the isolated mutant HMG-CoA synthases indicate that none of these is crucial to the chemistry that results in production of HMG-CoA. These results further distinguish the HMG-CoA synthase reaction from the related condensation of acyl-CoA substrates catalyzed by beta-ketothiolase.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0006-3002
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
1247
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
253-9
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1995
pubmed:articleTitle
Avian cytosolic 3-hydroxy-3-methylglutaryl-CoA synthase: evaluation of the role of cysteines in reaction chemistry.
pubmed:affiliation
Department of Biochemistry, Medical College of Wisconsin, Milwaukee 53226.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't