Abstact

Human liver glycogen phosphorylase (hlGP), a key enzyme in glycogen metabolism, is a valid pharmaceutical target for the development of new anti-hyperglycaemic agents for type 2 diabetes. Inhibitor discovery studies have focused on the active site and in particular on glucopyranose based compounds with a beta-1 substituent long enough to exploit interactions with a cavity adjacent to the active site, termed the beta-pocket. Recently, C-beta-d-glucopyranosyl imidazoles and 1, 2, 4-triazoles proved to be the best known glucose derived inhibitors of hlGP. Here we probe the beta-pocket by studying the inhibitory effect of six different groups at the para position of 3-(beta-d-glucopyranosyl phenyl)-5-phenyl-, 1, 2, 4-triazoles in hlGP by kinetics and X-ray crystallography. The most bioactive compound was the one with an amine substituent to show a K(i) value of 0.43 muM. Structural studies have revealed the physicochemical diversity of the beta-pocket providing information for future rational inhibitor design studies.