Gallic acid and d-catechin inhibitions of glutamic and arginine decarboxylases of Escherichia coli occur in both reversible and irreversible manners. Gallic acid competes with the substrate in glutamic decarboxylase and with pyridoxal phoshate in arginine decarboxylase, whereas the interactions of d-catechin in both enzymes are of noncompetitive nature with respects to both substrates and pyridoxal phosphate. Gallicacid and d-catechin combine with glutamic decarboxylase protein at different sites.
