Linked Life Data

8917463

Source:http://linkedlifedata.com/resource/pubmed/id/8917463

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1997-1-9
pubmed:abstractText
The pyridine nucleotide transhydrogenase of Escherichia coli catalyzes the reversible transfer of hydride ion equivalents between NAD+ and NADP+, coupled to translocation of protons across the cytoplasmic membrane. The role of histidine residues in catalysis was investigated by chemical modification with diethylpyrocarbonate and by site-directed mutagenesis. Diethylpyrocarbonate inhibited both hydride ion transfer and coupled proton translocation. Histidine residues were modified as shown spectroscopically and by the ability of hydroxylamine to cause reversal of inhibition. Complete inhibition of hydride ion transfer occurred following modification of 10 residues/enzyme molecule. Site-directed mutagenesis of single conserved histidine residues or the presence of substrates did not provide resistance to inhibition by diethylpyrocarbonate. It is concluded that diethylpyrocarbonate inhibition was a consequence of the structural changes brought about by modification of many histidine residues. With the exception of beta-subunit residue His91 (beta His91), in which mutation can result in specific loss of proton translocation activity [Glavas, N. A., Hou, C. & Bragg, P. D. (1995) Biochemistry 34, 7694-7702], site-directed mutation of the remaining conserved residues alpha His450, beta His161, beta His345 and beta His354 did not demonstrate a direct role for these residues in catalysis. Mutation of beta His161 had relatively little effect on the properties of the enzyme. By contrast, mutation of alpha His450, beta His345 and beta His354 caused major loss of enzyme activities which was probably due to alterations in the structure of the enzyme. These alterations were reflected in changes in the K(m) values for transhydrogenation.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0014-2956
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
241
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
611-8
pubmed:dateRevised
2011-11-17
pubmed:meshHeading
pubmed:year
1996
pubmed:articleTitle
The role of conserved histidine residues in the pyridine nucleotide transhydrogenase of Escherichia coli.
pubmed:affiliation
Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't