Abstract
α-Amylase was chemically bonded to a gel consisted of polyacrylamide (PAA) and dialdehyde starch (DAS) and its properties have been investigated. The enzymic activity of the immobilized α-amylase (IE) gel was determined by measuring the absorbance at 700 nm of solutions containing IE gel, a substrate, and KI-I2, being quite remarkable for the hydrolysis of starch at 40°C; the wet IE gel with a component ratio of 1: 1 showed an activity per unit weight corresponding to 0.024 mg of native α-amylase (NE). The wet gel, which was composed of networks of loosely cross-linked polymer and swelled with water, contained more than 98% of water. Thermal stability on the activity of the IE gel was superior to that of the NE in the range of 20-70°C at pH 7, although no apparent difference was observed between the activities of IE and NE in the range of pH 3-7 at 40°C. The Michaelis-Menten constant (Km) and maximal reaction rate (Vmax) of IE were estimated to be slightly larger than those of the NE. The enzymatic activities of the IE gel for starch hydrolysis were discussed in detail.
