Glutathione itself is not a catalyst but acts as a cofactor for several catalytic enzymes. A notable example is glutathione peroxidase, an enzyme that reduces lipid hydroperoxides to alcohols and free hydrogen peroxide to water. The reduction process involves the oxidation of GSH to glutathione disulfide (GSSG), which is then recycled back to GSH by the enzyme glutathione reductase. This cycle is crucial for maintaining the redox state within cells.