EPR detection of two protein-associated ubiquinone components (SQ(Nf) and SQ(Ns)) in the membrane in situ and in proteoliposomes of isolated bovine heart complex I.
Biochim Biophys Acta
; 1817(10): 1803-9, 2012 Oct.
Article
em En
| MEDLINE
| ID: mdl-22503829
ABSTRACT
The success of Sazanov's group in determining the X-ray structure of the whole bacterial complex I is a great contribution to the progress of complex I research. In this mini-review of 35years' history of my laboratory and collaborators, we characterized the function of protein-associated semiquinone molecules in the proton-pumping mechanism in complex I (NADH-quinone oxidoreductase). We have constructed most of the frame work of our hypothesis, utilizing EPR techniques before the X-ray structures of complex I were reported by Sazanov's and Brandt's groups. One of the semiquinones (SQ(Nf)) is extremely sensitive to a proton motive force imposed on the energy-transducing membrane, while the other (SQ(Ns)) is insensitive. Their sensitivity to rotenone inhibition also differs. These differences were exploited using tightly coupled bovine heart submitochondrial particles with a high respiratory control ratio (>8). We determined the distance between SQ(Nf) and iron-sulfur cluster N2 on the basis of their direct spin-spin interaction. We are extending this line of work using reconstituted bovine heart complex I proteoliposomes which shows a respiratory control ratio >5. Two frontier research groups support our view point based on their mutagenesis studies. High frequency (33.9GHz; Q-band) EPR experiments appear to favor our two-semiquinone model. This article is part of a Special Issue entitled 17th European Bioenergetics Conference (EBEC 2012).
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Modelos Moleculares
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Benzoquinonas
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Proteínas Mitocondriais
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Complexo I de Transporte de Elétrons
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Mitocôndrias Cardíacas
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Proteínas Musculares
Tipo de estudo:
Diagnostic_studies
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Prognostic_studies
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Risk_factors_studies
Limite:
Animals
Idioma:
En
Ano de publicação:
2012
Tipo de documento:
Article