Mechanism of control of cytochrome oxidase activity by the electrochemical-potential gradient.
Cytochrome c oxidation by bovine cytochrome oxidase embedded into liposomal vesicles with high respiratory control ratio (RCR = 6-10) has been studied by rapid-mixing experiments in the presence and absence of different ionophores. Kinetic analysis of the reaction indicates a linkage between the intrinsic activity of the enzyme, the efficiency of coupling and the electrochemical potential across the membrane. A simple model, based on two allosteric states with different catalytic properties in rapid equilibrium, is presented and successfully applied in the simulation of the observed time-course.
D000818:Animals; D002417:Cattle; D003574:Cytochrome c Group / Q000378:metabolism; D004563:Electrochemistry; D003576:Electron Transport Complex IV / Q000378:metabolism*; D007700:Kinetics; D008954:Models, Biological; D009206:Myocardium / Q000201:enzymology; D009550:Nigericin / Q000494:pharmacology; D010084:Oxidation-Reduction
D003574:Cytochrome c Group; D003576:Electron Transport Complex IV; D009550:Nigericin