title: Effect of b-c1-site inhibitors on the midpoint potentials of mitochondrial cytochromes b.
abstract: Anaerobic potentiometric titrations of b cytochromes have been carried out in beef heart submitochondrial particles in the presence of several specific inhibitors of electron transfer through the b-c1-site of the respiratory chain. Whereas antimycin shows no significant effect on the titration curve of cytochrome b-562, NoHOQnO is found to shift the Em of b-562 by 20-30 mV to the positive. Funiculosin raises the Em of b-562 by greater than 100 mV and also appears to bring about a minor shift of b-566 midpoint potential. In the presence of myxothiazol, both b cytochromes titrate with Em values 15-30 mV more positive than in the control.
mesh_terms: D000818:Animals; D000880:Anthraquinones / Q000494:pharmacology; D000968:Antimycin A / Q000031:analogs & derivatives / Q000494:pharmacology; D001665:Binding Sites; D002417:Cattle; D003580:Cytochromes / Q000502:physiology*; D014450:Electron Transport Complex III; D006912:Hydroxyquinolines / Q000494:pharmacology; D008689:Methacrylates; D008929:Mitochondria, Heart / Q000201:enzymology*; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors*; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors*; D010084:Oxidation-Reduction; D011199:Potentiometry; D011808:Quinone Reductases / Q000037:antagonists & inhibitors*; D013844:Thiazoles / Q000494:pharmacology
chemical_list: D000880:Anthraquinones; D003580:Cytochromes; D006912:Hydroxyquinolines; D008689:Methacrylates; D009097:Multienzyme Complexes; D013844:Thiazoles; C032456:antimycin; C010494:nonyl-4-hydroxyquinoline-N-oxide; C015286:funiculosin (anthraquinone); D000968:Antimycin A; C030517:myxothiazol; D009247:NADH, NADPH Oxidoreductases; D011808:Quinone Reductases; D014450:Electron Transport Complex III