title: Steady-state H+/O stoichiometry of liver mitochondria.
abstract: We have measured the H+/O stoichiometry of rat liver mitochondria respiring in a steady-state, using a novel method. This involves measuring the initial rate of H+ back-flow into mitochondria after respiratory inhibition, with the assumption that this is equal to the steady-state H+-ejection rate. Division by the steady-state O2-consumption rate yields the H+/O ratio. The H+/O values obtained were: 8.3 +/- 1.0 (mean +/- S.E.M.) for 3-hydroxybutyrate: 8.2 +/- 0.7 for glutamate plus malate; 6.0 +/- 0.2 for succinate; 4.1 +/- 0.3 for ascorbate/tetramethylphenylenediamine and 3.0 +/- 0.1 for ascorbate/ferrocyanide. These values correspond to H+/O stoichiometries for electron flow to oxygen from NAD+-linked substrates, succinate and cytochrome c of 8, 6 and 2 (charge/O ratio = 4) respectively.
mesh_terms: D000818:Animals; D000968:Antimycin A / Q000494:pharmacology; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D004579:Electron Transport / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008722:Methods; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000187:drug effects; D011190:Potassium Cyanide / Q000494:pharmacology; D011522:Protons; D051381:Rats
chemical_list: D011522:Protons; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D000968:Antimycin A; D011190:Potassium Cyanide