All are true about glutathione except
Glutathione (GSH) is an impoant antioxidant in plants, animals, fungi, and some bacteria and archaea. Glutathione is capable of preventing damage to impoant cellular components caused by reactive oxygen species such as free radicals, peroxides, lipid peroxides and heavy metals. It is a tripeptide with a gamma peptide linkage between the carboxyl group of the glutamate side chain and the amine group of cysteine, and the carboxyl group of cysteine is attached by the normal peptide linkage to a glycine. Glutathione is not an essential nutrient for humans since it can be synthesized in the body from the amino acids L-cysteine, L-glutamic acid, and glycine; it does not have to be present as a supplement in the diet. The sulfhydryl group (SH) of cysteine serves as a proton donor and is responsible for its biological activity. Cysteine is the rate-limiting factor in cellular glutathione biosynthesis since this amino acid is relatively rare in foods.
It is a tripeptide
It conves hemoglobin to methemoglobin
It conjugates xenobiotics
It is co-factor of various enzymes
Enzymes