Species difference in hydroperoxide-scavenging enzymes with special reference to glutathione peroxidase in guinea-pigs.

1. As guinea-pigs have been reported to have a markedly low activity of glutathione peroxidase (GSH-Px), the activity of other hydroperoxide-scavenging enzymes was investigated. 2. Catalase activity in guinea-pig tissues was 2-3 times higher than that of mice or rats. 3. Approximately 90% of catalase activity was found in the soluble fraction of guinea-pig liver, suggesting a compensatory role of catalase in removing H2O2 in the cytosol of guinea-pig tissues. 4. In erythrocytes, GSH-Px activity does not differ among rodents. This may reflect the fact that GSH-Px is the sole enzyme in the removal of organic hydroperoxides in erythrocytes where glutathione S-transferase activity is barely detectable.