THE ROLE OF SUPEROXIDE AND SINGLET OXYGEN IN LIPID PEROXIDATION |
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Authors: | Bruce A Svingen Fredrick O O'Neal Steven D Aust |
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Institution: | Department of Biochemistry, Michigan State University, East Lansing, MI 48824, U.S.A. |
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Abstract: | Abstract— An investigation into the mechanism of lipid peroxidation catalyzed by xanthine oxidase showed a dependence upon superoxide, singlet oxygen and adenosine 5'-diphosphate chelated iron (ADP-Fe3+). In the absence of ADP-Fe3+ or in the presence of superoxide dismutase there is complete inhibition of enzymatic peroxidation. Initiation of peroxidation likely occurs through an ADP-perferryl ion complex formed by ADP-Fe3+ and superoxide. Use of the singlet oxygen trapping agent 2,5-diphenylfuran showed that singlet oxygen does not participate in the initiation of peroxidation but rather in the propagation of peroxidation. The mechanisms of NADPH-cytochrome P450 reductase-catalyzed and ADP-Fe2+ catalyzed lipid peroxidation parallel that of xanthine oxidase in that initiation occurs through a superoxide dismutase-sensitive reaction and that singlet oxygen is present during propagation of lipid peroxidation. |
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