sulfur containing modified residue modified L-cysteine residue S-(gamma-glutamyl-cysteinyl-glycyl)-cysteine (2S)-2-amino-5-([(2R)-1-([2-([(2R)-2-amino-2-carboxyethyl]sulfanyl)-2-oxoethyl]amino)-1-oxo-3-sulfanylpropan-2-yl]amino)-5-oxopentanoic acid 289.0732421875 289.30999755859375 392.082427978515625 392.44000244140625 A protein modification that effectively converts an L-cysteine residue to S-(gamma-glutamyl-cysteinyl-glycyl)-cysteine. ACT_SITE S-(gamma-glutamyl-cysteinyl-glycyl)-cysteine intermediate C C 10 H 15 N 3 O 5 S 1 C 13 H 20 N 4 O 6 S 2 MOD:01969 PSI-MOD S-(gamma-glutamyl-cysteinyl-glycyl)-cysteine S-(glutathion-1-yl)-L-cysteine natural