Inhibition of the phosphate-stimulated cytochromec oxidase activity by thiophosphate |
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Authors: | Stephen Manon Nadine Camougrand Martine Guerin |
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Affiliation: | (1) Institut de Biochimie Cellulaire et de Neurochimie du Centre National de la Recherche Scientifique, 1 rue Camille Saint-Saens, F-33077 Bordeaux Cedex, France;(2) Université de Bordeaux II, 146 rue Leo Saignat, Bordeaux, France |
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Abstract: | Yeast and mammalian cytochromec oxidase activity is inhibited by thiophosphate. This inhibition was observed when using either whole mitochondria or the isolated or reconstituted enzyme. The kinetics of the reduction reaction enabled us to demonstrate that thiophosphate acted on th electrons transfer between hemesa anda3. With whole mitochondria, phosphate alone stimulated respiration. The inhibition induced by thiophosphate was suppressed by phosphate only in mitochondria, but not when the isolated enzyme was used. The possibility of a kinetic regulation is discussed.Abbreviations CCCP p-carbonylcyanidem-chlorophenylhydrazone - TMPD N,N,N,N-tetramethylp-phenylenediamine - SPi thiophosphate |
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Keywords: | Cytochromec oxidase thiophosphate phosphate kinetic regulation |
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