The influence of porphyrins on iron-catalysed generation of hydroxyl radicals

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 porphyrin...

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Bibliographic Details
Published in:Biochemical journal 1988-02, Vol.250 (1), p.197-201
Main Authors: Van Steveninck, J, Boegheim, J P, Dubbelman, T M, Van der Zee, J
Format: Article
Language:English
Subjects:
Catalysis
Electron Spin Resonance Spectroscopy
Free Radicals
Hematoporphyrin Derivative
Hematoporphyrins - pharmacology
Horseradish Peroxidase - metabolism
Hydrogen Peroxide - metabolism
Hydroxides - metabolism
Hydroxyl Radical
Hypoxanthine
Hypoxanthines - metabolism
Iron - pharmacology
NADP - metabolism
Porphyrins - pharmacology
Superoxide Dismutase - pharmacology
Xanthine Oxidase - metabolism
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Summary: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.
ISSN:0264-6021
1470-8728
DOI:10.1042/bj2500197