Glutathione disulfide

Glutathione disulfide (GSSG) is a disulfide derived from two glutathione molecules.

In living cells, glutathione disulfide is reduced into two molecules of glutathione with reducing equivalents from the coenzyme NADPH. This reaction is catalyzed by the enzyme glutathione reductase. Antioxidant enzymes, such as glutathione peroxidases and peroxiredoxins, generate glutathione disulfide during the reduction of peroxides such as hydrogen peroxide (H₂O₂) and organic hydroperoxides (ROOH):