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  • Title: Inhibition of proton pumping in membrane reconstituted bovine heart cytochrome c oxidase by zinc binding at the inner matrix side.
    Author: Martino PL, Capitanio G, Capitanio N, Papa S.
    Journal: Biochim Biophys Acta; 2011 Sep; 1807(9):1075-82. PubMed ID: 21658365.
    Abstract:
    A study is presented on the effect of zinc binding at the matrix side, on the proton pump of purified liposome reconstituted bovine heart cytochrome c oxidase (COV). Internally trapped Zn(2+) resulted in 50% decoupling of the proton pump at level flow. Analysis of the pH dependence of inhibition by internal Zn(2+) of proton release in the oxidative and reductive phases of the catalytic cycle of cytochrome c oxidase indicates that Zn(2+) suppresses two of the four proton pumping steps in the cycle, those taking place when the 2 OH(-) produced in the reduction of O(2) at the binuclear center are protonated to 2 H(2)O. This decoupling effect could be associated with Zn(2+) induced conformational alteration of an acid/base cluster linked to heme a(3).
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