Oxidized_glutathione
Glutathione disulfide
Chemical compound
Glutathione disulfide (GSSG) is a disulfide derived from two glutathione molecules.[1]
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.[2]
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):[3]
- 2 GSH + ROOH → GSSG + ROH + H2O
Other enzymes, such as glutaredoxins, generate glutathione disulfide through thiol-disulfide exchange with protein disulfide bonds or other low molecular mass compounds, such as coenzyme A disulfide or dehydroascorbic acid.[4]
- 2 GSH + R-S-S-R → GSSG + 2 RSH
The GSH:GSSG ratio is therefore an important bioindicator of cellular health, with a higher ratio signifying less oxidative stress in the organism. A lower ratio may even be indicative of neurodegenerative diseases, such as Parkinson's disease (PD) and Alzheimer's disease.[5]