ABSTRACT
The initial step in the degradation of glutathione (GSH) and glutathione derivatives is the cleavage of the γ-glutamyl bond by a membrane-bound enzyme γ-glutamyl transpeptidase or GGT (EC.2.3.2.2). 1 The active site of GGT is oriented on the outer face of the cell membrane 2 and it catalyzes three types of reactions (see References 1, 3, and 4 for reviews):
