A COOPERATIVE MODEL FOR PROTONMOTIVE HEME-COPPER OXIDASES - THE ROLE OF HEME A IN THE PROTON PUMP OF CYTOCHROME-C-OXIDASE

Oxide-reductions of metal centers in cytochrome c oxidase are linked t o pK shifts of acidic groups in the enzyme (redox Bohr effects). The l inkage at heme a results in proton uptake from the inner space upon re duction and proton release in the external space upon oxidation of the metal. The relationship of this process to the features of the proton pump in cytochrome c oxidase and its atomic structure revealed by X-r ay crystallography to 2.8-2.3 Angstrom resolution is examined. A mecha nism for the proton pump of cytochrome c oxidase, based on cooperative coupling at heme a, is proposed. (C) 1998 Federation of European Bioc hemical Societies.