Catalytic intermediates of cytochrome bd terminal oxidase at steady-state: ferryl and oxy-ferrous species dominate. - RIIP - Réseau International des Instituts Pasteur Accéder directement au contenu
Article Dans Une Revue Biochimica et Biophysica Acta (BBA) - Enzymology Année : 2011

Catalytic intermediates of cytochrome bd terminal oxidase at steady-state: ferryl and oxy-ferrous species dominate.

Résumé

The cytochrome bd ubiquinol oxidase from Escherichia coli couples the exergonic two-electron oxidation of ubiquinol and four-electron reduction of O(2) to 2H(2)O to proton motive force generation by transmembrane charge separation. The oxidase contains two b-type hemes (b(558) and b(595)) and one heme d, where O(2) 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 O(2) 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 b(558). 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.
Fichier principal
Vignette du fichier
Borisov2011.pdf (1.02 Mo) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte
Loading...

Dates et versions

pasteur-00975925 , version 1 (09-04-2014)

Identifiants

Citer

Vitaliy B Borisov, Elena Forte, Paolo Sarti, Alessandro Giuffrè. Catalytic intermediates of cytochrome bd terminal oxidase at steady-state: ferryl and oxy-ferrous species dominate.. Biochimica et Biophysica Acta (BBA) - Enzymology, 2011, 1807 (5), pp.503-9. ⟨10.1016/j.bbabio.2011.02.007⟩. ⟨pasteur-00975925⟩

Collections

RIIP RIIP_FCB
24 Consultations
141 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More