Zn2+ binding to the cytoplasmic side of Paracoccus denitrificans cytochrome c oxidase selectively uncouples electron transfer and proton translocation1

FEBS Letters

Ostermann, Thomas²  Müller, Hannelore²  Ruitenberg, Maarten¹  Kannt, Aimo² 

[1] Max Planck Institute of Biophysics, Department of Biophysical Chemistry, Kennedyallee 70, D-60596 Frankfurt am Main, Germany;Max Planck Institute of Biophysics, Department of Molecular Membrane Biology, Heinrich-Hoffmann-Str. 7, D-60528 Frankfurt am Main, Germany

关键词: Cytochrome c oxidase;    Proton pumping;    Zn2+ binding;    Black lipid membrane;    Proton slip;    CCCP;    carbonyl cyanide m-chlorophenylhydrazine;    COV;    cytochrome c oxidase containing vesicle;    COX;    cytochrome c oxidase;    RCR;    respiratory control ratio;   

DOI  :  10.1016/S0014-5793(01)02719-3

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Using a combination of stopped-flow spectrophotometric proton pumping measurements and time-resolved potential measurements on black lipid membranes, we have investigated the effect of Zn²⁺ ions on the proton transfer properties of Paracoccus denitrificans cytochrome c oxidase. When zinc was enclosed in the interior of cytochrome c oxidase containing liposomes, the H/e stoichiometry was found to gradually decrease with increasing Zn²⁺ concentration. Half-inhibition of proton pumping was observed at [Zn²⁺] _i =75 μM corresponding to about 5–6 Zn²⁺ ions per oxidase molecule. In addition, there was a significant increase in the respiratory control ratio of the proteoliposomes upon incorporation of Zn²⁺. Time-resolved potential measurements on a black lipid membrane showed that the electrogenic phases slowed down in the presence of Zn²⁺ correspond to phases that have been attributed to proton uptake from the cytoplasmic side and to proton pumping. We conclude that Zn²⁺ ions bind close to or within the two proton transfer pathways of the bacterial cytochrome c oxidase.

【 授权许可】

Unknown