| Literature DB >> 2833235 |
J Van Steveninck1, J P Boegheim, T M Dubbelman, J Van der Zee.
Abstract
Uroporphyrin I, haematoporphyrin and haematoporphyrin derivative had no effect on O2-. generation during oxidation of hypoxanthine by xanthine oxidase and on the formation of hydroxyl radicals (OH.) in the hypoxanthine/xanthine oxidase/Fe3+-EDTA/deoxyribose system. On the other hand, these porphyrins strongly inhibited O2-. formation in a horseradish peroxidase/H2O2/NADPH mixture, whereas they augmented OH. generation in this system after addition of Fe3+-EDTA. Experimental evidence suggests that these observations should be ascribed to the formation of a porphyrin anion radical in the horseradish peroxidase/NADPH system. The formation of this anion radical was confirmed by e.s.r. spectroscopy. This radical is apparently unable to reduce cytochrome c, but it can replace O2-. in the OH.-generating Haber-Weiss reaction.Entities:
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Year: 1988 PMID： 2833235 PMCID： PMC1148832 DOI： 10.1042/bj2500197
Source DB: PubMed Journal: Biochem J ISSN： 0264-6021 Impact factor: 3.857