Full article: Mimetics of the Selenoenzyme Glutathione Peroxidase: Novel Structures and Unusual Catalytic Mechanisms Intravenous Glutathione Enhances Cycling Time Trial Performance Hammer Nutrition 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 Glutathione: The Fountain of Youth Renew Health & Wellness