title: Single catalytic site model for the oxidation of ferrocytochrome c by mitochondrial cytochrome c oxidase.
abstract: A single catalytic site model is proposed to account for the multiphasic kinetics of oxidation of ferrocytochrome c by cytochrome c oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1). This model involves nonproductive binding of substrate to sites near the catalytic site on cytochrome c oxidase for cytochrome c, decreasing the binding constant for cytochrome c at the catalytic site. This substrate inhibition results in an increase in the first-order rate constant for the dissociation of the ferricytochrome c-cytochrome c oxidase complex, the rate-limiting step in the steady-state turnover of electrons between cytochrome c and cytochrome c oxidase in the spectrophotometric assay, yielding increases in the initial rate as well as the Michaelis constant--namely, multiple kinetic phases.
mesh_terms: D000818:Animals; D001665:Binding Sites; D002417:Cattle; D003201:Computers; D003574:Cytochrome c Group / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007700:Kinetics; D008929:Mitochondria, Heart / Q000201:enzymology; D010084:Oxidation-Reduction; D011485:Protein Binding; D013053:Spectrophotometry
chemical_list: D003574:Cytochrome c Group; D003576:Electron Transport Complex IV