Kinetic and thermodynamic analysis of the inhibitory effects of maltose, glucose, and related carbohydrates on wheat β-amylase

Enzyme Microb Technol. 2013 Apr 10;52(4-5):251-7. doi: 10.1016/j.enzmictec.2013.01.010. Epub 2013 Feb 8.


Inhibition of wheat β-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±0.01M, 0.22±0.09M, and 1.41±0.17M, respectively. The inhibitor constant (Ki) and the thermodynamic parameters such as changes in Gibbs energy (ΔG), enthalpy (ΔH), and entropy (ΔS) 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°C with respective Ki values of 0.33±0.02M and 0.12±0.03M. In contrast, both sugars exhibited uncompetitive inhibition at pH 9 at a temperature of 25°C with Ki values of 0.21±0.03M for glucose and 0.11±0.04M for maltose. The pH-dependence of the inhibition type and Ki 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.

MeSH terms

  • Carbohydrates / pharmacology
  • Food Technology
  • Glucose / pharmacology
  • Hydrogen-Ion Concentration
  • Kinetics
  • Maltose / pharmacology
  • Plant Proteins / antagonists & inhibitors*
  • Plant Proteins / metabolism
  • Starch / metabolism
  • Temperature
  • Thermodynamics
  • Triticum / enzymology*
  • beta-Amylase / antagonists & inhibitors*
  • beta-Amylase / metabolism


  • Carbohydrates
  • Plant Proteins
  • Maltose
  • Starch
  • beta-Amylase
  • Glucose