http://www.cnr.it/ontology/cnr/individuo/prodotto/ID11873
Catalytic intermediates of cytochrome bd terminal oxidase at steady-state: ferryl and oxy-ferrous species dominate (Articolo in rivista)
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- Catalytic intermediates of cytochrome bd terminal oxidase at steady-state: ferryl and oxy-ferrous species dominate (Articolo in rivista) (literal)
- Anno
- 2011-01-01T00:00:00+01:00 (literal)
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- Borisov VB; Forte E; Sarti P; Giuffrè A. (literal)
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- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russian Federation; Department of Biochemical Sciences, CNR Institute of Molecular Biology and Pathology and Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, I-00185 Rome, Italy. (literal)
- Titolo
- Catalytic intermediates of cytochrome bd terminal oxidase at steady-state: ferryl and oxy-ferrous species dominate (literal)
- Abstract
- The cytochrome bd ubiquinol oxidase from Escherichia coli couples the exergonic two-electron oxidation of ubiquinol and four-electron reduction of O2 to 2H2O to proton motive force generation by transmembrane charge separation. The oxidase contains two b-type hemes (b558 and b595) and one heme d, where O2 is captured and converted to water through sequential formation of a few intermediates. The spectral features of the isolated cytochrome bd at steady-state have been examined by stopped-flow multiwavelength absorption spectroscopy. Under turnover conditions, sustained by O2 and dithiothreitol (DTT)-reduced ubiquinone, the ferryl and oxy-ferrous species are the mostly populated catalytic intermediates, with a residual minor fraction of the enzyme containing ferric heme d and possibly one electron on heme b558. These findings are unprecedented and differ from those obtained with mammalian cytochrome c oxidase, in which the oxygen intermediates were not found to be populated at detectable levels under similar conditions [M.G. Mason, P. Nicholls, C.E. Cooper, The steady-state mechanism of cytochrome c oxidase: redox interactions between metal centres, Biochem. J. 422 (2009) 237-246]. The data on cytochrome bd are consistent with the observation that the purified enzyme has the heme d mainly in stable oxy-ferrous and ferryl states. The results are here discussed in the light of previously proposed models of the catalytic cycle of cytochrome bd. (literal)
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