Gamma-glutamyl transpeptidase (GGTP) activii y was measured in the homogenate of penile foreskin, usingｒ-glutamyl-p-nitroanilide, as a substrate, and it was found that (GGTP) activity, was present in the epidermis and dermis, being more active in the former.
The optimum pH for the enzyme was 8.5-9.0 in Tris buffer, which was similar to those of the rat kidney and human serum enzymes. It was also revealed that glycylglycine was the most effective activator of the enzyme and some activation was also observed in the presence of L-glutamine. But L-methionine, L-homoserine, L-glutamic acid, L-arginine, L-aspartic acid, glycine and L-valine inhibited the activity, suggesting that these amino acids do not act as acceptors of r-glutamyl moiety. The enzyme was remarkably inhibited by bromosulphalein, oxidised glutathione, and by L-serine in the presence of borate, and the inhibitions were more severe than is the case with the rat kidney and human serum enzymes.
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