On The Mechanism of Energy Coupling in Cytochrome Oxidase
Highly purified cytochrome oxidase from beef heart mitochondria without any supplementation catalyzes the coupling of the oxidation of ferrocytochrome c by O2 to the transport of monovalent or divalent cations (Green et al., 1980; Fry and Green, 1980a). This finding established that cytochrome oxidase was a complete energy-coupling system and that coupling took only one form—the coupling of electron transfer to cation transport. Cytochrome oxidase was ideally suited to probe the mechanism of energy coupling. The components and structure of the electron transfer chain were well defined, the subunit structure of the complex was firmly established, the stoichiometry of the oxidative reaction (oxidation of ferrocytochrome c by O2) was known, the assay of cytochrome oxidase activity was sufficiently selective that it was possible to measure this activity as readily in mitochondria as in dispersions of the purified oxidase, and finally and most importantly ion transport is the least complicated expression of a coupled process.
KeywordsElectron Transfer Cytochrome Oxidase Cation Transport Energy Coupling Subunit Structure
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