title: Cytochrome c-mediated electron transfer between ubiquinol-cytochrome c reductase and cytochrome c oxidase. Kinetic evidence for a mobile cytochrome c pool.
abstract: Ubiquinol oxidase has been reconstituted from ubiquinol-cytochrome c reductase (Complex III), cytochrome c and cytochrome c oxidase (Complex IV). The steady-state level of reduction of cytochrome c by ubiquinol-2 varies with the molar ratios of the complexes and with the presence of antimycin in a way that can be quantitatively accounted for by a model in which cytochrome c acts as a freely diffusible pool on the membrane. This model was based on that of Kröger & Klingenberg [(1973) Eur. J. Biochem. 34, 358-368] for ubiquinone-pool behaviour. Further confirmation of the pool model was provided by analysis of ubiquinol oxidase activity as a function of the molar ratio of the complexes and prediction of the degree of inhibition by antimycin.
mesh_terms: D000968:Antimycin A / Q000031:analogs & derivatives / Q000494:pharmacology; D003574:Cytochrome c Group / Q000378:metabolism*; D004579:Electron Transport; D014450:Electron Transport Complex III; D003576:Electron Transport Complex IV / Q000378:metabolism*; D007700:Kinetics; D008956:Models, Chemical; D009097:Multienzyme Complexes / Q000378:metabolism*; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D011808:Quinone Reductases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D003574:Cytochrome c Group; D009097:Multienzyme Complexes; C032456:antimycin; D000968:Antimycin A; D009247:NADH, NADPH Oxidoreductases; D011808:Quinone Reductases; C030914:ubiquinol-1 oxidase; D003576:Electron Transport Complex IV; D014450:Electron Transport Complex III