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KMID : 0385219970070030065
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Korean Journal of Gerontology
1997 Volume.7 No. 3 p.65 ~ p.69
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Protevtive Role of Anionic Compounds in the Inactivation of Cu, Zn-SOD by H2O2
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Kim Heung-Nam
Kwak Hahn-Shik
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Abstract
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It is known that bovine erythrocyte SOD is inactivated by H2O2, slowly and irreversibly, but is protected against inactivation by several anionic compounds. However, the mechanism of the inactivation by H2O2 and the protection by anionic compounds are not fully understood. In this study, in order to investigate the possible involvement of hydroxyl radicals in the inactivation of Cu, Zn-SOD by H2O2, the peroxidative activity of Cu, Zn-SOD was studied. We analyzed the activity of Cu, Zn-SOD that catalyzes the formation of OH·-radicals with two different approaches : the oxidation reaction of ferrocytochrome c(Fe2+) to ferricytochrome c(Fe3+) and the oxidation of a chromogen spin probe, ABTS(2, 2’-azinobis-3-ethylbenzthiazoline-6- sulfonate). In addition to the common activity of Cu, Zn-SOD that catalyzes the superoxide dismutation, the inactivation by its own reaction product H2O2 and the peroxidase activity together indicate that the Cu, Zn-SOD has the activity that catalyzes the formation of OH·-radicals using H2O2 as substrates. Protection effects of several radical scavengers such as formate, aspartate, and glutamate was also investigated. These radical scavengers protected the enzyme against inactivation by H2O2, whereas ethanol and PBN(N-tert-butyl-α-phenylnitron) did not. The results together indicate that anionic scavengers have easy access to the positively charged active channel of Cu, Zn-SOD and are thus in position to intercept the newly formed OH·-radicals. In the physiological conditions, the glutamate and the aspartate may act as radical scavengers and become a relatively stable radicals.
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KEYWORD
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Cu, Zn-SOD, OH·-radical, H2O2, Anionic compounds
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