The role of cytochrome a in the proton pump of cytochrome-c oxidase.
Cytochrome-c oxidase of bovine heart mitochondria was depleted of copper A by dialysis against 1 M KCN in the presence of dodecylmaltoside. There was no difference of the pH-dependence of the midpoint potential between the intact and the copper-depleted enzyme. Oxidation of reduced cytochrome a2+a3(3+).CN complex released about 1 proton/electron in the medium at pH 7.6. This release was inhibited by N,N'-dicyclohexylcarbodiimide. Again there was no difference between the intact and Cu-depleted enzyme. This limits the role of copper A in the mechanism of the proton pump. On the other hand, these experiments showed that cytochrome a could be a component of the proton pump.
D000818:Animals; D002417:Cattle; D003300:Copper / Q000502:physiology; D017936:Cytochrome a Group; D003580:Cytochromes / Q000502:physiology*; D004024:Dicyclohexylcarbodiimide / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy; D003576:Electron Transport Complex IV / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D007473:Ion Channels / Q000502:physiology*; D008929:Mitochondria, Heart / Q000201:enzymology*; D010084:Oxidation-Reduction; D011199:Potentiometry; D011522:Protons
D017936:Cytochrome a Group; D003580:Cytochromes; D007473:Ion Channels; D011522:Protons; D004024:Dicyclohexylcarbodiimide; D003300:Copper; D003576:Electron Transport Complex IV