Gaining insights into α‑amylase inhibition by glucose through mathematical modeling and analysis of the hydrolysis kinetics of gelatinized corn starch dispersions.

Abstract

The inhibitory effect of glucose on the activity of α‑amylase used for starch hydrolysis was explored in this study. Four gelatinized corn starch dispersions (5 g/100 mL) containing different glucose concentrations (0.5, 1.0, 2.0 and 4.0 g/100 mL) and a control without added glucose were subjected to enzymatic hydrolysis with α‑amylase (0.33 IU/mL) for 2 h. The hydrolysis kinetics showed that the limiting hydrolysis advance was reduced as glucose concentration increased. A Michaelis-Menten scheme was used for developing a mathematical model of the hydrolysis kinetics. The mathematical model predicted that the maximum hydrolysis value was consequence of the inhibition of the enzyme activity by the initial glucose load added to the gelatinized starch dispersions and by the glucose produced by amylolytic action. FTIR analysis of the Amide I band showed that glucose disrupted the secondary structure of the α‑amylase, an effect that could be related to the inhibition of the enzymatic activity.