The glutathione peroxidases

There are several proteins in mammalian cells that can metabolize hydrogen peroxide and lipid hydroperoxides. These proteins include four selenium-con taining glutathione peroxidases that are found in different cell fractions and tissues of the body. This review considers the structure and distributi on of the selenoperoxidases and how this relates to their biological functi on. The functions of the selenoperoxidases were originally studied in syste ms where their activity was manipulated by changing dietary selenium levels . More recently, molecular techniques have allowed overexpression of seleno peroxidases in cell lines and animals. Additionally, cellular glutathione p eroxidase knockout mice have been used to investigate the functions of this protein. From this work it is clear that the selenoperoxidases are involve d in cell antioxidant systems. However, they also have more subtle function s in ensuring the regulation and formation of arachadonic acid metabolites that are derived from hydroperoxide intermediates. The range of biological processes, which are potentially dependent on optimal selenoperoxidase acti vity in mammals, emphasises the importance of achieving adequate selenium i ntake in the diet.