The oxidation of yeast Complex III. Evidence for a very rapid electron equilibration between cytochrome c1 and the iron-sulfur center.
The reoxidation of reduced cytochrome c1 by potassium ferricyanide follows pseudo-first order kinetics with k = 4 x 10(4) M-1 s-1. However, the reoxidation of this cytochrome in two-electron reduced Complex III does not follow any simple rate law although the overall rate of reaction is essentially unchanged. The observed kinetics can be well fitted with a model in which ferricyanide reacts exclusively with cytochrome c1 together with very rapid electron transfer from the reduced iron-sulfur center to cytochrome c1. Neither removal of coenzyme Q from the complex nor prior incubation with antimycin A had any effect on the observed kinetics of reoxidation.
D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003574:Cytochrome c Group / Q000031:analogs & derivatives*; D003575:Cytochromes c1 / Q000378:metabolism*; D004579:Electron Transport; D005292:Ferricyanides / Q000494:pharmacology; D007700:Kinetics; D008928:Mitochondria / Q000032:analysis; D010084:Oxidation-Reduction; D014451:Ubiquinone / Q000378:metabolism; D015003:Yeasts / Q000032:analysis
D003574:Cytochrome c Group; D005292:Ferricyanides; D014451:Ubiquinone; D003575:Cytochromes c1; C028033:potassium ferricyanide