Ovothiol replaces glutathione peroxidase as a hydrogen peroxide scavenger in sea urchin eggs.
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.
Turner
E
E
Department of Biochemistry, University of Washington, Seattle 98195.
Hager
L J
LJ
Shapiro
B M
BM
D000603:Amino Acids, Sulfur / Q000378:metabolism*; D000818:Animals; D002374:Catalase / Q000378:metabolism; D004220:Disulfides / Q000378:metabolism; D005260:Female; D005306:Fertilization; D005978:Glutathione / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism*; D007700:Kinetics; D008762:Methylhistidines; D009249:NADP / Q000378:metabolism; D010063:Ovum / Q000378:metabolism*; D010084:Oxidation-Reduction; D012617:Sea Urchins
D000603:Amino Acids, Sulfur; D004220:Disulfides; D008762:Methylhistidines; C050085:ovothiol C; D009249:NADP; D002374:Catalase; D005979:Glutathione Peroxidase; D005978:Glutathione