Comparison of the effects of superoxide dismutase and cytochrome c on luminol chemiluminescence produced by xanthine oxidase-catalyzed reactions.
Superoxide dismutase (superoxide: superoxide oxidoreductase, EC 1.15.1.1) (SOD) and ferricytochrome c are used to check the effects on luminol chemiluminescence induced by a xanthine or hypoxanthine/xanthine oxidase/oxygen system. Luminol chemiluminescence has been attributed to superoxide anion radical (O2.-) in this system. From kinetic studies on the light intensity vs. time curves it is demonstrated that addition of SOD into the system does not affect the mechanism of O2.- generation, whilst ferricytochrome c dramatically alters the time-course of the reaction. This is interpreted as the effect of cytochrome c redox cycling by reaction with H2O2, modifying oxy-radical generation in the reaction medium. Also, an alternative mechanism for luminol chemiexcitation is proposed under certain experimental conditions.
Radi
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Department of Biochemistry, Faculty of Medicine, Universidad de la República, Montevideo, Uruguay.
Rubbo
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Prodanov
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D002384:Catalysis; D003574:Cytochrome c Group / Q000494:pharmacology*; D019271:Hypoxanthine; D007042:Hypoxanthines / Q000378:metabolism; D007700:Kinetics; D008163:Luminescent Measurements; D008165:Luminol / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D011724:Pyridazines / Q000378:metabolism*; D013056:Spectrophotometry, Ultraviolet; D013482:Superoxide Dismutase / Q000494:pharmacology*; D013481:Superoxides / Q000378:metabolism; D019820:Xanthine; D014969:Xanthine Oxidase / Q000378:metabolism*; D014970:Xanthines / Q000378:metabolism
D003574:Cytochrome c Group; D007042:Hypoxanthines; D011724:Pyridazines; D014970:Xanthines; D013481:Superoxides; D019820:Xanthine; D019271:Hypoxanthine; D008165:Luminol; D013482:Superoxide Dismutase; D014969:Xanthine Oxidase; D010100:Oxygen