Linked Life Data

2061339

Source:http://linkedlifedata.com/resource/pubmed/id/2061339

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
19
pubmed:dateCreated
1991-8-7
pubmed:abstractText
To evaluate potential catalytic mechanism for thioltransferase thiol-disulfide exchange reactions, seven pig liver mutants were constructed by site-directed mutagenesis. All the expressed enzymes, including wild-type and mutants with the exception of the inactive mutant, ETT-C22S, were variably inhibited by iodoacetamide, and similar results were obtained when these enzymes were preincubated with GSH. However, when preincubated with S-sulfocysteine or hydroxyethyl disulfide, the activity of the enzymes was totally or partially protected against inhibition by iodoacetamide, with the exception of the mutants, ETT-C25S and ETT-C25A. When simultaneously pretreated with GSH and S-sulfocysteine, all enzymes were highly protected. Isoelectric focusing analysis of the above preincubation mixtures showed that different enzyme-substrate intermediates occurred. Using radioactively labeled substrates, [U-14C]cystine and [glycine-2-3H] GSH, enzyme-substrate intermediates were detected. These data indicate that reduced thioltransferase reacts first with disulfide substrates, then with a thiol substrate, e.g. GSH. The formation of either enzyme-substrate mixed disulfide or protein intramolecular disulfide protected the enzyme from inactivation by iodoacetamide. Based on the experimental results, alternative methods of the catalytic mechanism for thioltransferases are proposed.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
5
pubmed:volume
266
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
12766-71
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Catalytic mechanism of thioltransferase.
pubmed:affiliation
Department of Biochemistry, Michigan State University, East Lansing 48824.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.