Localization of a ferricyanide-reactive site of cytochrome b− c1 complex, possibly of cytochrome b or ubisemiquinone, at the outer face of submitochondrial particles

• Published in: FEBS letters 1984-07, Vol.172 (2), p.261-266
• Main Authors: Kunz, Wolfram S., Konstantinov, Alexander, Tsofina, Liliya, Liberman, Efim A.
• Format: Article
• Language: English
• Subjects: Animals; Antimycin A - analogs & derivatives; Antimycin A - pharmacology; b Membrane potential; Biological and medical sciences; b− c1 site inhibitor; Cattle; Cell structures and functions; Coenzymes; Cytochrome; Cytochrome b Group - metabolism; Electron Transport; Electron Transport Complex III; Ferricyanides - metabolism; Ferricyanides - pharmacology; Fundamental and applied biological sciences. Psychology; Membrane Potentials - drug effects; Mitochondria - enzymology; Mitochondria and cell respiration; Mitochondria, Heart - metabolism; Molecular and cellular biology; Multienzyme Complexes - metabolism; NADH, NADPH Oxidoreductases - metabolism; Oxidation-Reduction; Oxygen Consumption - drug effects; Q-cycle; Quinone Reductases - metabolism; Redox center topography; Respiratory chain; Submitochondrial Particles - enzymology; Ubiquinone - analogs & derivatives; Ubiquinone - metabolism
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(84)81137-0

When succinate oxidation by submitochondrial particles is blocked by antimycin, NoHOQnO or funiculosin, addition of ferricyanide restores oxygen uptake coupled to membrane potential generation. The effect of ferricyanide is abolished by mucidin or myxothiazol, as well as by KCN. The data strongly favor a cyclic redox loop mechanism in site 2 and show that either heme of the ferrous cytochrome b or ubisemiquinone formed in the QH 2-oxidizing center of complex b− c 1 is accessible to ferricyanide at the outer (M) side of the submitochondrial particle membrane.