Linked Life Data

3032620

Source:http://linkedlifedata.com/resource/pubmed/id/3032620

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1987-6-25
pubmed:abstractText
In this paper a study is presented of the characteristics of redox-linked proton ejection exhibited by isolated beef-heart cytochrome c oxidase incorporated in asolectin vesicles. The enzyme was 90% oriented 'right-side out' as in the mitochondrial membrane. The effects on the H+/e- stoichiometry of the modalities of activation of electron flow, the pH of the medium and its ionic composition were investigated. The results obtained show that, whilst ferrocytochrome c pulses of the aerobic oxidase vesicles at neutral pH and in the presence of saturating concentrations of valinomycin and K+ to ensure charge compensation produced H+/e- ratios around 1 (as has been shown previously), oxygen pulses of reduced anaerobic vesicles supplemented with cytochrome c, gave H+/e- ratios around 0.3. The H+/e- ratios exhibited, with both reductant and oxidant pulses, a marked pH dependence. Maximum values were observed at pH 7.0-7.7, which decreased to negligible values at acidic pH with apparent pKa of 6.7-6.3. Mg2+ and Ca2+ caused a marked depression of the H+/e- ratio, which in the presence of these cations and after a few ferrocytochrome pulses, became negligible. Analysis of cytochrome c oxidation showed that the modalities of activation of electron flow and divalent cations exerted profound effects on the kinetics of cytochrome c oxidation by oxidase vesicles. The observations presented seem to provide interesting clues for the nature and mechanism of redox-linked proton ejection in reconstituted cytochrome c oxidase.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0014-2956
pubmed:author
pubmed:issnType
Print
pubmed:day
4
pubmed:volume
164
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
507-16
pubmed:dateRevised
2007-7-23
pubmed:meshHeading
pubmed:year
1987
pubmed:articleTitle
Characteristics of the redox-linked proton ejection in beef-heart cytochrome c oxidase reconstituted in liposomes.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't