title: Thermodynamic control of electron flux through mitochondrial cytochrome bc1 complex.
abstract: The redox states of exogenously added ubiquinone-2 and cytochrome c, and the protonmotive force (delta p) of rat liver mitochondria were measured as the respiration rate was titrated with the uncoupler carbonyl cyanide p-trifluoromethoxyphenyl-hydrazone. The force ratio delta Eh/delta p across the bc1 complex was close to 1:1 in State 4, indicating an H+/e- stoichiometry of 1:1 for the cytochrome bc1 complex, excluding protons moved by pool ubiquinone. Assuming a constant stoichiometry the rate of electron transport increased linearly with the disequilibrium (delta Eh - delta p) across the complex.
authors.forename: G C
authors.initials: GC
authors.lastname: Brown
authors.forename: M D
authors.initials: MD
authors.lastname: Brand
mesh_terms: D000818:Animals; D016227:Benzoquinones; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D003574:Cytochrome c Group / Q000494:pharmacology; D004579:Electron Transport / Q000187:drug effects; D014450:Electron Transport Complex III; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D008930:Mitochondria, Liver / Q000187:drug effects / Q000201:enzymology*; D009097:Multienzyme Complexes / Q000378:metabolism*; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects; D011808:Quinone Reductases / Q000378:metabolism*; D011809:Quinones / Q000494:pharmacology; D051381:Rats; D013816:Thermodynamics; D014451:Ubiquinone / Q000494:pharmacology
chemical_list: D016227:Benzoquinones; D003574:Cytochrome c Group; D009097:Multienzyme Complexes; D011809:Quinones; D014451:Ubiquinone; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D009247:NADH, NADPH Oxidoreductases; D011808:Quinone Reductases; D014450:Electron Transport Complex III; C025204:Ubiquinone Q2; C034257:duroquinone