Glutathione peroxidase (GPx) is an important antioxidant selenium-containing enzyme that was first discovered by Mills in 1957 which had the activity that protects red blood cells against H2O. In the 1960s, glutathione peroxidase activity was detected in other tissues and it was shown to catabolize organic hydroperoxides in addition to H2O2.
Glutathione peroxidases are a family of phylogenetically related oxidoreductases distributed in all living domains. Glutathione peroxidase belongs to the class of selenocysteine compound because it binds four atoms of selenium and provides the catalytic activity of glutathione peroxidase. It needs glutathione as a co-substrate.
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 is present at the catalytic site of glutathione peroxidase, and selenium availability regulates glutathione peroxidase enzyme activity.
Glutathione peroxidase is present in the cytosol and in mitochondria, and has a high degree of affinity for H2O2 compared with catalase. Glutathione peroxidase reduces and breaks down not only H2O2 but also lipid peroxide (LOOH) by catalyzing a redox reaction with reduced glutathione (GSH), which serves as an electron donor.
Glutathione peroxidase enzyme
