Proton translocation by the respiratory haem-copper oxidases

Cytochrome c oxidase is a molecular machine that transduces respiratory energy into an electrochemical proton gradient across the mitochondrial or bacterial membrane. Reduction of O-2 to water takes place at a binuclear haem-copper site, to which four electrons are transferred from cytochrome c on the outer side of the membrane, and four protons from the inside. An additional and equal contribution to Delta mu(H+) generation comes from so-called proton pumping, where four H+ ions are translocated across the membrane per O-2 reduced. Some recent progress in research on the mechanism of energy transduction; by this class of enzymes is reviewed. (C) 1998 Elsevier Science BN.