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

β-Galactosidase (β-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°C, pH 6 for the immobilized β-galactosidase I and 52°C, pH 6 for the immobilized β-galactosidase II, respectively. The operational pH range was increased. Kinetic constants (Km, Vmax and Ea) for the free and bound enzymes, with ONPG as substrate, were studied. Results showed that Km and Vmax of immobilized enzymes were decreased while Ea 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.