Z-GLU-GLY-OH

Z-L-A-GLUTAMYL-L-GLYCINE

Z-L-ALPHA-GLUTAMYL-L-GLYCINE

4-(benzyloxycarbonylamino)-5-(carboxymethylamino)-5-keto-valeric acid

5-(carboxymethylamino)-5-oxo-4-(phenylmethoxycarbonylamino)pentanoic acid