3.2.1.2	(alpha-D-glucopyranosyl-(1-4))n-alpha-D-glucopyranose + H2O = (alpha-D-glucopyranosyl-(1-4))n-2-alpha-D-glucopyranose + alpha-D-glucopyranosyl-(1-4)-beta-D-glucopyranose	roles of Glu186 and Glu380 as general acid and general base catalyst in the catalytic reaction, substrate binding and reaction mechanism	666019