Immobilization and characterization of beta-galactosidase from the plant gram chicken bean (Cicer arietinum). Evolution of its enzymatic actions in the hydrolysis of lactose

beta-Galactosidase (beta-D-galactosidase galactohydrolase, EC 3.2.1.23) iso lated and purified from gram chicken bean was immobilized on cross-linked p olyacrylamide gel. The activity yield was high and attained up to 72%. Comp ared with the free enzyme, the immobilized enzyme had a wider operational p H range and better thermal stability. Lyophilized pieces exhibited good sta bility when stored at room temperature for 60 days and a favorable operatio nal stability when used eight times repeatedly without loss of enzymatic ac tivity under the same conditions. Kinetic data (K-m, V-m, and E-a) for the free and the immobilized enzymes were determined using O-nitrophenyl-beta-D -galactoside (ONPG) and lactose as substrates. The result of time courses o f hydrolysis of lactose showed that beta-galactosidase from the plant gram chicken bean would have a promising application in the hydrolysis of lactos e in milk.