Cytochrome oxidase-catalyzed superoxide generation from hydrogen peroxide. |
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| Authors: | T V Ksenzenko MYu Y" >Vygodina,V Berka,E K Ruuge,A A Konstantinov |
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| Affiliation: | A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, USSR. |
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| Abstract: | Superoxide dismutase is shown to affect spectral changes observed upon cytochrome c oxidase reaction with H2O2, which indicates a possibility of O2- radicals being formed in the reaction. Using DMPO as a spin trap, generation of superoxide radicals from H2O2 in the presence of cytochrome oxidase is directly demonstrated. The process is inhibited by cyanide and is not observed with a heat-denatured enzyme pointing to a specific reaction in the oxygen-reducing centre of cytochrome c oxidase. The data support a hypothesis on a catalase cycle catalyzed by cytochrome c oxidase in the presence of excess H2O2 (Vygodina and Konstantinov (1988) Ann. NY Acad. Sci., 550, 124-138): (formula: see text) |
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