Alpha-glucosidase (AGH) from the small intestine of rat was immobilized onto a glutaraldehyde (GA) activated NH(2)-96 well microplate to establish a convenient and rapid AGH inhibition assay system. After AGH immobilization, remaining GA groups were blocked by beta-alanine to induce a negative charge on the surface of the well. The AGH-plate showed an enzyme activity of 444 nU/well under an assayed condition at 37 degrees C for 2 h using 0.3 mM 4-methylumbelliferyl-alpha-D-glucopyranoside as a fluorogenic substrate. Inhibitory powers of voglibose and acarbose as therapeutic AGH inhibitors were successfully evaluated to have IC(50) values of 13 and 114 nM, respectively.