Glutathione consists of cysteine plus glutamate plus ?

Ans. is 'c' i.e., Glycine Glutathione Glutathione is a tripeptide made up of glutamate, cysteine and glycine (T-glutamyl-cysteinyl-glycine).Glutathione is present in all mammalian cells except neurons.The sulphydryl (-SH) group of cysteine residue is the reactive poion of glutathione which can undergo oxidation and reduction.Thus, glutathione may exist as the reduced (G-SH) or oxidized form (G-S-S-G) and can play a role in some oxidation-reduction reactions.In oxidized form two molecules of glutathione are linked by disulfide bond.Glutathione has following function : -i) It helps in keeping some enzyme in active state by preventing the oxidation of sulphydryl (-SH) group of enzyme.ii) It helps in detoxification of H2O2 by reducing it. Superoxide anion (O2) first conveed to H2O2 by superoxide dismutase. H2O2 is then reduced to H2O2 by glutathione perioxidase, a reaction requires reduced glutathione. Thus, glutathione scavenges free radicals and superoxide anion.iii) It helps in detoxification of xenobiotics by their conjugation (conjugation reaction).iv) Reduced form of glutathione (GSH) with a free sulphydryl (-SH) group serves as a redox buffer, regulating redox state of the cell.v) Reduced glutathione is essential for maintaining the normal structure of RBCs and for keeping hemoglobin iron in ferrous state (prevents formation of methemoglobin).vi) It is involved in the transpo of amino acids across the cell membane of kidney and intestine.