Linked Life Data

8547262

Source:http://linkedlifedata.com/resource/pubmed/id/8547262

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1996-2-22
pubmed:abstractText
The molecular mechanism by which proton pumping is coupled to electron transfer in cytochrome c oxidase has not yet been determined. However, several models of this process have been proposed which are based on changes occurring in the vicinity of the redox centers of the enzyme. Recently, a model was described in which a well-conserved tyrosine residue in subunit I (Y422) was proposed to undergo ligand exchange with the histidine ligand (H419) of the high-spin heme a3 during the catalytic cycle, allowing both residues to serve as part of a proton transporting system. Site-directed mutants of Y422 have been constructed in the aa3-type cytochrome c oxidase of Rhodobacter sphaeroides to test this hypothesis (Y422A, Y422F). The results demonstrate that Y422 is not an essential residue in the electron transfer and proton pumping mechanisms of cytochrome c oxidase. However, the results support the predicted proximity of Y422 to heme a3, as now confirmed by crystal structure. In addition, it is shown that the pH-dependent reversed electron transfer between heme a and heme a3 is normal in the Y422F mutant. Hence, these data also demonstrate that Y422 is not the residue previously postulated to interact electrostatically with heme a3, nor is it responsible for the unique EPR characteristics of heme a in this bacterial oxidase.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
23
pubmed:volume
35
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
824-8
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1996
pubmed:articleTitle
A ligand-exchange mechanism of proton pumping involving tyrosine-422 of subunit I of cytochrome oxidase is ruled out.
pubmed:affiliation
School of Chemical Sciences, University of Illinois, Urbana 61801, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't