Selenium and peroxide metabolism

Abstract

□ Out of the growing number of so far known mammalian selenoproteins four are peroxidases. Their common catalytic mechanism involves redox shuttling of a selenocysteine residue in the active site, where it forms a characteristic catalytic triad with hydrogen-bonded tryptophan and glutamine residues. □ These peroxidases differ in tissue distribution, substrate specifity, regulation, responsiveness to selenium restriction, and likely in their biological role. □ Cytosolic glutathione peroxidase, which predominates in balancing hydroperoxide toxicity, rapidly declines in selenium deficiency. Prophylactic selenium supplementation is considered reasonable also in asymptomatic moderate selenium deficiency whenever a clinical condition known to cause oxidative stress has to be anticipated.