Interaction of L-gamma-glutamyl-alpha,beta-dehydroamino acids with gamma-glutamyl transpeptidase.

Three gamma-glutamyl alpha,beta-dehydroamino acids: L-gamma-glutamyl-dehydroalanine, L-gamma-glutamyl-(Z)-dehydrobutyrine and L-gamma-glutamyl-(E)-dehydrobutyrine have been prepared as potential ligands (inhibitors or substrates) for gamma-glutamyl transpeptidase (GGT). Both isomers of gamma-glutamyl-dehydrobutyrines proved to be inhibitors of GGT, slightly better than the saturated analogue, L-gamma-glutamyl-L-butyrine. However, their solvolysis catalysed by the enzyme is slower than that of the latter. L-gamma-Glutamyl-(E)-dehydrobutyrine seems to be a more active compound in both enzymatic tests. L-gamma-Glutamyl-dehydroalanine elicited only low inhibitory activity and, moreover, was unstable under conditions of the solvolysis test.