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ArticlesCopyright © 1988 by American Association for the Advancement of Science
Ovothiol replaces glutathione peroxidase as a hydrogen peroxide scavenger in sea urchin eggs
Department of Biochemistry, University of Washington, Seattle 98195.
Despite its potential toxicity, H2O2 is used as an extracellular oxidant by Stronglylocentrotus purpuratus eggs to cross-link their fertilization envelopes. These eggs contain 5 mM 1-methyl-N alpha,N alpha-dimethyl-4-mercaptohistidine (ovothiol C), which reacts with H2O2. In consuming H2O2 and being reduced by glutathione, ovothiol acts as a glutathione peroxidase and replaces the function of the enzyme in eggs. The ovothiol system is more effective than egg catalase in destroying H2O2 at concentrations produced during fertilization and constitutes a principal mechanism for preventing oxidative damage at fertilization.
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Science. ISSN 0036-8075 (print), 1095-9203 (online)