Inhibition of α-amylase activity by cellulose: Kinetic analysis and nutritional implications

We report on inhibition of alpha-amylase activity by cellulose based on in vitro experiments. The presence of cellulose in the hydrolysing medium reduced the initial velocity of starch hydrolysis in a concentration dependent manner. alpha-Amylase adsorption to cellulose was reversible, attaining equilibrium within 30 min of incubation, and showed a higher affinity at 37 degrees C compared to 20 and 0 degrees C. The adsorption was almost unchanged in the presence of maltose (2.5-20 mM) but was hindered in the presence of excess protein, suggesting non-specific adsorption of alpha-amylase to cellulose. Kinetic analyses of alpha-amylase hydrolysis of maize starch in the presence of cellulose showed that the inhibition is of a mixed type. The dissociation constant (K-ic) of the El complex was found to be ca. 3 mg/mL. The observed inhibition of alpha-amylase activity suggests that cellulose in the diet can potentially attenuate starch hydrolysis. (C) 2015 Elsevier Ltd. All rights reserved.