Immobilization of β-galactosidase from Cicer arietinum (gram chicken bean) and its catalytic actions

beta-Galactosidase (beta-D-galactosidase galactohydrolase EC 3.2.1.23) isolated and purified from Cicer arietinum (gram chicken bean) was immobilized on two kinds of modified resin D202 with glutaraldehyde. Both the immobilized enzymes had high protein-binding capacity and high yield of enzyme activity. Kinetics results showed that the enzyme activity attained its maximum at 57 degrees C, pH 6 for the immobilized beta-galactosidase I and 52 degrees C; pH 6 for the immobilized beta-galactosidase II, respectively. The operational pH range was increased. Kinetic constants (K-m, V-max and E-a) for the free and bound enzymes, with ONPG as substrate, were studied. Results showed that K-m and V-max of immobilized enzymes were decreased while E-a of them was increased. The effects of some compounds and organic solvents for the free and immobilized enzymes were discussed. Inhibitory constants for raffinose, lactose and D-galactose, which were all reversible inhibitors of the enzymes, were also obtained. (C) 1999 Elsevier Science Ltd. All rights reserved.