A kinetic model to explain the maximum in alpha-amylase activity measurements in the presence of small carbohydrates.
The effect of the presence of several small carbohydrates on the measurement of the alpha-amylase activity was determined over a broad concentration range. At low carbohydrate concentrations, a distinct maximum in the alpha-amylase activity versus concentration curves was observed in several cases. At higher concentrations, all carbohydrates show a decreasing alpha-amylase activity at increasing carbohydrate concentrations. A general kinetic model has been developed that can be used to describe and explain these phenomena. This model is based on the formation of a carbohydrate-enzyme complex that remains active. It is assumed that this complex is formed when a carbohydrate binds to alpha-amylase without blocking the catalytic site and its surrounding subsites. Furthermore, the kinetic model incorporates substrate inhibition and substrate competition. Depending on the carbohydrate type and concentration, the measured alpha-amylase activity can be 75% lower than the actual alpha-amylase activity. The model that has been developed can be used to correct for these effects in order to obtain the actual amount of active enzyme.
Baks
Tim
T
Food and Bioprocess Engineering Group, Wageningen University and Research Centre, P.O. Box 8129, 6700 EV, Wageningen, The Netherlands. tim.baks@wur.nl
Janssen
Anja E M
AE
Boom
Remko M
RM
D001665:Binding Sites; D002241:Carbohydrates / Q000737:chemistry*; D007700:Kinetics; D008956:Models, Chemical; D011485:Protein Binding; D013379:Substrate Specificity; D000516:alpha-Amylases / Q000737:chemistry*
D002241:Carbohydrates; D000516:alpha-Amylases