Catalyzes the transfer of the gamma-glutamyl moiety of glutathione (GSH) and other gamma-glutamyl compounds to amino acids and peptides. Major GSH-degrading enzyme, catalyzing the hydrolytic release of L-glutamate from GSH. Plays a role in the turnover of the vacuolar GSH, serving as an alternative nitrogen source during nitrogen starvation (By similarity). {ECO:0000250, ECO:0000269|PubMed:15920625}.