Kinetics for the Hydrolysis of Soluble Starch by Glucoamylase and Application to an Immobilized Enzyme System

The hydrolysis of starch by glucoamylase proceeds by step-wise removal of glucose units from the nonreducing ends of the starch chain; and the number of available substrate molecules may be unchanged in the course of the degradation. The rate of the hydrolysis generally increases with increase in MW of the substrate. In view of these aspects, a simple practical equation, consisting of modified Michaelis-Menten kinetics with product inhibition, is presented for the hydrolysis of soluble starch (1). It is assumed that the concentration of substrate does not change during the conversion, while the values of kinetic parameters Vm and Km vary linearly with the reduction of the average MW of siSbstrate from the values for starch toward those for maltose.