The biochemistry of selenoproteins

There currently are 7 known bacterial selenoenzymes. All but thiolase contain selenocysteine (Se‐Cys), presumably at the active site, and all but thiolase catalyze oxidation‐reduction reactions. Selenide appears to be a central intermediate in selenium (Se) metabolism in animals, and it may be the precursor used for formation of the Se‐Cys moiety in glutathione peroxidase (GSH‐Px). The incorporation of Se into GSH‐Px appears to occur via a post‐translational mechanism, but the nature and extent of Se‐Cys formation in higher animals has not been established. GSH‐Px deficiency remains a logical explanation for a number of Se‐deficiency signs, but other known selenoproteins and other functions may match up with defects apparently not prevented by GSH‐Px.