The phosphate potential maintained by mitochondria in State 4 is proportional to the proton-motive force

• Published in: FEBS letters 1985-01, Vol.179 (2), p.278-282
• Main Authors: Woelders, Henri, van der Zande, Wim J., Colen, Anne-Marie A.F., Wanders, Ronald J.A., van Dam, Karel
• Format: Article
• Language: English
• Subjects: Adenine Nucleotides - metabolism; Adenylate Kinase - metabolism; Animals; AP5A, P1,P5-di(adenosine-5'-)pentaphosphate; Biological and medical sciences; Cell structures and functions; DNP, 2,4-dinitrophenol; Electrochemistry; Energy Metabolism; Energy transduction; FCCP, carbonyl cyanide p-trifluoromethoxyphenylhydrazone; Fundamental and applied biological sciences. Psychology; Intracellular Membranes - physiology; liver; Localised chemiosmotic coupling; Malonates - pharmacology; Mitochondria; Mitochondria and cell respiration; Mitochondria, Liver - drug effects; Mitochondria, Liver - physiology; Molecular and cellular biology; Oxidation-Reduction; phosphate; Phosphates - metabolism; Potassium - metabolism; Proton-motive force Phosphate potential ATP synthase stoichiometry; Proton-motive force Phosphate potentialATP synthase stoichiometry; protonmotive force; Protons; Rats; S13, 5-chloro-3-tert-butyl-2'-chloro-4'-nitrosalicylanilide; Succinates - metabolism; Succinic Acid; Uncoupling Agents - pharmacology; ΔG ex p, extramitochondrial phosphate potential; Δμ̃H+, the electrochemical potential difference for protons between two separate spaces
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(85)80534-2

Evidence is presented for a proportional relationship between the extramitochondrial phosphate potential (Δ G ex p) and the proton-motive force (Δ \ ̃ gm H + ) across the mitochondrial membrane in rat-liver mitochondria oxidising succinate in State 4, when Δ \ ̃ gm H + is varied by addition of uncouplers or malonate. This relationship was found when precautions were taken to minimise interference with the determination of Δ G p ex and Δ \ ̃ gm H + by intramitochondrial nucleotides, adenylate kinase activity, the quenching method, and Δ \ ̃ gm H + -dependent changes in matrix volume. A non-proportional Δ G p ex/Δ \ ̃ gm H + relationship was obtained when these precautions were omitted. Our results do not support mosaic protonic coupling, but are not necessarily in conflict with other localised coupling schemes.