title: [Differences in the action of antimycin and 2-nonyl-4-hydroxyquinoline N-oxide on oxidation-reduction of mitochondrial cytochromes b].
abstract: The differences in the effects of two similar electron transfer inhibitors, antimycin and 2-nonyl-4-hydroxyquinoline N-oxide (HOQNO) on the reactions of cytochromes b are described. In the cyanide-inhibited submitochondrial particles of bovine heart, HOQNO strongly stimulates cytochrome b reduction by ascorbate in the presence of redox mediators, e. g. N,N,N',N'-tetramethylparaphenylene diamine, 2,6-dichlorophenolindophenol, diaminodurol and phenazine methosulfate; this effect can be reversed by antimycin. Addition of both inhibitors to the submitochondrial particles aerobically equilibrated with succinate/fumarate redox buffer at E = +54 mV in the presence of cyanide results in a similar reduction of cytochromes b, which in the case of antimycin is readily reversed by phenazine methosulfate but is resistant to this redox mediator in the presence of HOQNO. The latter causes additional reduction of cytochrome b562 in the argone atmosphere, the effect being reversed by antimycin. In the presence of HOQNO the anaerobic redox titration curve of cytochrome b562 is shifted towards a high potential region by 20-30 mV. An additional reduction of cytochromes b induced by HOQNO can be due to superposition of two effects, i. e. extra-reduction of cytochromes b566 and b562 requiring O2 and a true positive shift of E0 of cytochrome b562.
mesh_terms: D000818:Animals; D000968:Antimycin A / Q000494:pharmacology*; D002417:Cattle; D003573:Cytochrome b Group / Q000378:metabolism*; D004579:Electron Transport; D006912:Hydroxyquinolines / Q000494:pharmacology*; D007700:Kinetics; D008928:Mitochondria / Q000378:metabolism*; D008929:Mitochondria, Heart / Q000378:metabolism; D010084:Oxidation-Reduction; D013367:Submitochondrial Particles / Q000187:drug effects / Q000378:metabolism*
chemical_list: D003573:Cytochrome b Group; D006912:Hydroxyquinolines; C010494:nonyl-4-hydroxyquinoline-N-oxide; D000968:Antimycin A
vernacular_title: Razlichiia v deĭstvii antimitsina i N-oksida 2-nonil-4-oksikhinolina na okislenie-vosstanovlenie mitokhondrial'nykh tsitokhromov b.