title: Role of cooperative H(+)/e(-) linkage (redox bohr effect) at heme a/Cu(A) and heme a(3)/Cu(B) in the proton pump of cytochrome c oxidase.
abstract: It is a pleasure to contribute to the special issue published in honor of Vladimir Skulachev, a distinguished scientist who greatly contributes to maintain a high standard of biochemical research in Russia. A more particular reason can be found in his work, where observations anticipating some ideas presented in my article were reported. Cytochrome c oxidase exhibits protonmotive, redox linked allosteric cooperativity. Experimental observations on soluble bovine cytochrome c oxidase are presented showing that oxido-reduction of heme a/Cu(A) and heme a(3)/Cu(B) is linked to deprotonation/protonation of two clusters of protolytic groups, A(1) and A(2), respectively. This cooperative linkage (redox Bohr effect) results in the translocation of 1 H(+)/oxidase molecule upon oxido-reduction of heme a/Cu(A) and heme a(3)/Cu(B), respectively. Results on liposome-reconstituted oxidase show that upon oxidation of heme a/Cu(A) and heme a(3)/Cu(B) protons from A(1) and A(2) are released in the outer aqueous phase. A(1) but not A(2) appears to take up protons from the inner aqueous space upon reduction of the respective redox center. A cooperative model is presented in which the A(1) and A(2) clusters, operating in close sequence, constitute together the gate of the proton pump in cytochrome c oxidase.
authors.affiliation: Institute of Bioenergetics and Biomembranes, Department of Medical Biochemistry and Biology, University of Bari, Bari, 70124, Italy. papabchm@cimedoc.uniba.it.
authors.forename: S
authors.initials: S
authors.lastname: Papa
mesh_terms: D000818:Animals; D003300:Copper / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D004579:Electron Transport; D003576:Electron Transport Complex IV / Q000737:chemistry / Q000502:physiology*; D004583:Electrons; D006418:Heme / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D010084:Oxidation-Reduction; D017494:Proton Pumps / Q000737:chemistry / Q000502:physiology*; D011522:Protons
chemical_list: D017494:Proton Pumps; D011522:Protons; D006418:Heme; D003300:Copper; D003576:Electron Transport Complex IV