Stable selones in glutathione peroxidase like catalytic cycle of selenonicotinamide derivative Organic & Biomolecular Chemistry (RSC Publishing) TJ. Glutathione peroxidase is an important enzyme in cellular antioxidant defense systems, detoxifying peroxides and hydroperoxides. As a component of the glutathione cycle, it protects the liver from reactive oxygen metabolites. Selenocysteine The Glutathione System: A Journey from Cyanobacteria to Higher Eukaryotes Ascorbate Glutathione Pathway Encyclopedia MDPI