INHIBITION OF RABBIT GASTRIC GLUCOSAMINE SYNTHETASE-ACTIVITY BY CU2+,ZN2+ AND SE4+

The effects of Fe2+, Cu2+, Zn2+ and Se4+ on the activity of glucosamin e synthetase, the rate-limiting enzyme of mucus synthesis, in rabbit g astric corporal mucosa were examined. Cu2+, Zn2+ and Se4+ inhibited th e glucosamine synthetase activity at concentrations ranging from 1 to 10 mu M (Cu2+, 8-98% inhibition; Zn2+, 10-99% inhibition; Se4+, 32-89% inhibition). The inhibitory effects of these three ions were much str onger than that of UDP-N-acetylglucosamine known as a representative i nhibitor of the glucosamine synthetase activity (10 mu M, 52% inhibiti on). Fe2+ had no significant effect on the glucosamine synthetase acti vity up to 100 mu M. These results suggest that Cu2+, Zn2+ and Se4+ ca n be potent inhibitors of gastric glucosamine synthetase activity.