Proton pumping by cytochrome c oxidase is coupled to peroxidase half of its catalytic cycle

FEBS Letters

Papa, S²  Capitanio, N²  Vygodina, T.V¹  Konstantinov, A.A¹ 

[1]A.N. Belozerskiy Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russia

[2]Institute of Medical Chemistry and Biochemistry, University of Bari, Bari, Italy

关键词: Cytochrome oxidase;    Proton pumping;    Peroxidase;    Proteoliposome;    Oxygen intermediate;    Membrane potential;    COX;    cytochrome c oxidase;    COV;    cytochrome c oxidase vesicles;    CCCP;    carbonyl cyanide m-chlorophenyl hydrazone;    O;    R;    P;    F;    oxidized;    reduced;    peroxy and ferryl-oxo forms of cytochrome c oxidase;   

DOI  :  10.1016/S0014-5793(97)00649-2

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The four-electron reaction cycle of cytochrome oxidase is comprised of an eu-oxidase phase in which the enzyme receives the first two electrons and reduces oxygen to bound peroxide and a peroxidase phase in which the peroxy state formed in the eu-oxidase half of the cycle is reduced by the 3rd and 4th electrons to the ferryl-oxo state and oxidized form, respectively. Here we show that the ferrocyanide-peroxidase activity of cytochrome c oxidase incorporated in phospholipid vesicles is coupled to proton pumping. The H⁺/e ⁻ ratio for the ferrocyanide-peroxidase partial reaction is twice higher than for the overall ferrocyanide-oxidase activity and is close to 2. These results show that proton pumping by COX is confined to the peroxidase part of the enzyme catalytic cycle (transfer of the 3rd and 4th electron) whereas the eu-oxidase part (transfer of the first two electrons) may not be proton pumping.

【 授权许可】

Unknown