title: Coupling site I and the rotenone-sensitive ubisemiquinone in tightly coupled submitochondrial particles.
abstract: The rotenone-sensitive g = 2.00 low temperature EPR signal attributed to ubisemiquinone is observed in submitochondrial particles during coupled electron transfer from NADH to oxygen and from succinate to NAD+. The signal is seen only in the presence of oligomycin added to induce the respiratory control (7-9 with NADH and 3-4 with succinate) and it disappears in the presence of uncouplers (CCCP or gramicidin D). No reduction of the iron-sulfur center N-2 in the presence of 20 mM succinate and cyanide is observed, thus suggesting that N-2 is not in equilibrium with the ubiquinone pool. A hypothesis is proposed on delta mu H+ generation coupled with electron transfer between iron-sulfur center N-2 and the ubiquinone pool.
authors.affiliation: Department of Biochemistry, School of Biology, Moscow State University, USSR.
authors.forename: A B
authors.initials: AB
authors.lastname: Kotlyar
authors.forename: V D
authors.initials: VD
authors.lastname: Sled
authors.forename: D S
authors.initials: DS
authors.lastname: Burbaev
authors.forename: I A
authors.initials: IA
authors.lastname: Moroz
authors.forename: A D
authors.initials: AD
authors.lastname: Vinogradov
mesh_terms: D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D003067:Coenzymes; D004578:Electron Spin Resonance Spectroscopy; D004579:Electron Transport; D009243:NAD / Q000378:metabolism; D016660:NAD(P)H Dehydrogenase (Quinone); D009840:Oligomycins / Q000494:pharmacology; D010084:Oxidation-Reduction; D011808:Quinone Reductases / Q000378:metabolism*; D012402:Rotenone / Q000494:pharmacology*; D013367:Submitochondrial Particles / Q000187:drug effects / Q000378:metabolism*; D013386:Succinates / Q000378:metabolism; D014451:Ubiquinone / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D003067:Coenzymes; D009840:Oligomycins; D013386:Succinates; D012402:Rotenone; D009243:NAD; D014451:Ubiquinone; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D016660:NAD(P)H Dehydrogenase (Quinone); D011808:Quinone Reductases; C024989:coenzyme Q10