- a crystalline, water-soluble peptide of glutamic acid, cysteine, and glycine, C10H17N3O6S, found in blood and in animal and plant tissues, and important in tissue oxidations and in the activation of some enzymes.
- a tripeptide consisting of glutamic acid, cysteine, and glycine: important in biological oxidations and the activation of some enzymes. Formula: C 10 H 17 N 3 O 6 S