Abstract: Anα-amylase inhibitor (WBAI) glycoprotein was extracted and purified from white kidney beans. It had stronger stability to pH and temperature in comparison with other proteins. When incubated at pH6.8 for 10 min, it presented strongest inhibitory activity toα-amylase(ID50=1.7×10-5 mol/L).Its inhibitory activity is closely related to the concentration of the inhibitor. In the case of small inhibitor concentration, there would be a linear relationship for the combination of the inhibitor and amylase. The activity curve was drifted with increasing concentration of the inhibitor. Based on the studies of lineweaver-Burk plot, the WBAI presents an uncompetitive inhibition toα-amylase. The inhibitory constant(Ki) is 9.4125×10-6 mol/L.

Key words: white kidney bean &alpha, -amylase inhibitor(WBAI)； stability； inhibition kinetics； inhibitory type； inhibitoryc onstant；