Individual Differences in Activity of Glutathione Peroxidase and Catalase Studied in Monozygotic Twins Discordant for Smoking

Abstract

1 Cigarette smoke contains free radicals. The enzymes glutathione peroxidase (GSH-px) and catalase are important parts of the anti-oxidative protecting system. 2 Ten pairs of monozygotic twins, who were discordant for smoking, were analysed in order to determine their erythrocyte glutathione peroxidase and catalase activities and their plasma concentrations of selenium. 3 Analysis of variance (ANOVA) revealed that the difference in activities of catalase and glutathione peroxidase was much less within pairs than between pairs, indicating a large individual variation due to genetic expression or shared environment and no major effect from smoking. 4 The plasma selenium levels of the investigated twins revealed sufficient intake of selenium to maintain maximal activity of GSH-px in erythrocytes. The mean±s.d. selenium concentration in plasma for smokers was 98 ± 16 μg 1-1 and for non-smokers 111 ± 16 μg 1-1. There was no correlation between plasma selenium and glutathione peroxidase in erythrocytes.