Inhibition of wheat beta-amylase (WBA) by glucose and maltose was studied by kinetics and thermodynamics. The inhibitory effects of fructose, difructose, sucrose, trehalose, cellobiose, acarbose, and 1-deoxynojirimycin on WBA were also evaluated. The half maximal inhibitory concentrations (IC50) of acarbose, maltose and glucose were 0.06 +/- 0.01 M, 0.22 +/- 0.09 M, and 1.41 +/- 0.17 M, respectively. The inhibitor constant (K-i) and the thermodynamic parameters such as changes in Gibbs energy (Delta G), enthalpy (Delta H), and entropy (Delta S) of the dissociation reactions of the WBA-glucose and WBA-maltose complexes were temperature and pH-dependent. The dissociation reactions were endothermic and enthalpy-driven. Both glucose and maltose behaved as competitive inhibitors at pH 3.0 and 5.4 at a temperature of 25 degrees C with respective K-i values of 0.33 +/- 0.02 M and 0.12 +/- 0.03 M. In contrast, both sugars exhibited uncompetitive inhibition at pH 9 at a temperature of 25 degrees C with K-i values of 0.21 +/- 0.03 M for glucose and 0.11 +/- 0.04 M for maltose. The pH-dependence of the inhibition type and K-i values indicate that the ionizing groups of WBA influence drastically the interaction with these carbohydrates. This evidence enables us to consider temperature and pH in the WBA-catalyzed hydrolysis to manipulate the inhibition by end-product, maltose, and even by glucose. (C) 2013 Elsevier Inc. All rights reserved.