1. Glutathione (GSH) is a tripeptide that contains an unusual peptide linkage between the amine
group of cysteine (which is attached by normal peptide linkage to a glycine) and the carboxyl
group of the glutamate sidechain. It is an antioxidant, preventing damage to important cellular
components caused by reactive oxygen species such as free radicals and peroxides.
2. Thiol groups are reducing agents, existing at a concentration of approximately 5 mM in animal
cells. Glutathione reduces disulfide bondsformed within cytoplasmic proteins to cysteines by
serving as an electron donor. In the process, glutathione is converted to its oxidized form
glutathione disulfide (GSSG), also called L(-)-Glutathione.
3. Glutathione is found almost exclusively in its reduced form, since the enzyme that reverts it fromits oxidized form, glutathione reductase, is constitutively active and inducible upon oxidative
stress. In fact, the ratio of reduced glutathione to oxidized glutathione within cells is often used as a measure of cellular toxicity .
