Control by cytochrome c oxidase of the cellular oxidative phosphorylation system depends on the mitochondrial energy state.
Recent measurements of the flux control exerted by cytochrome c oxidase on the respiratory activity in intact cells have led to a re-appraisal of its regulatory function. We have further extended this in vivo study in the framework of the Metabolic Control Analysis and evaluated the impact of the mitochondrial transmembrane electrochemical potential (Deltamu(H+)) on the control strength of the oxidase. The results indicate that, under conditions mimicking the mitochondrial State 4 of respiration, both the flux control coefficient and the threshold value of cytochrome oxidase are modified with respect to the uncoupled condition. The results obtained are consistent with a model based on changes in the assembly state of the oxidative phosphorylation enzyme complexes and possible implications in the understanding of exercise-intolerance of human neuromuscular degenerative diseases are discussed.
Department of Biomedical Science, University of Foggia, 71100 Foggia, Italy.
Claudia
C
Piccoli
Rosella
R
Scrima
Domenico
D
Boffoli
Nazzareno
N
Capitanio
D001205:Ascorbic Acid / Q000378:metabolism; D045744:Cell Line, Tumor; D003576:Electron Transport Complex IV / Q000378:metabolism*; D004734:Energy Metabolism / Q000502:physiology*; D006801:Humans; D007700:Kinetics; D008564:Membrane Potentials / Q000502:physiology; D008928:Mitochondria / Q000502:physiology*; D051336:Mitochondrial Membranes / Q000502:physiology; D009840:Oligomycins / Q000494:pharmacology; D010085:Oxidative Phosphorylation / Q000187:drug effects*; D010101:Oxygen Consumption; D013772:Tetramethylphenylenediamine / Q000494:pharmacology; D014634:Valinomycin / Q000494:pharmacology
D009840:Oligomycins; D014634:Valinomycin; D003576:Electron Transport Complex IV; D013772:Tetramethylphenylenediamine; D001205:Ascorbic Acid