A new approach to evaluate immobilization of B-galactosidase on eupergit c: structural, kinetic, and thermal characterization

Abstract

This study aimed to evaluate B-galactosidase immobilization. For this purpose, the ionic strength of the buffer, reaction time, amount of the immobilization support, and pH were evaluated by a central composite design. Assay 8, which consisted of 1.5 mol L −1 phosphate buffer (pH 7.5) and a reaction time of 2 h, produced the maximum yield. Eupergit® C (400 mg) was subsequently use as an immobilization support. Immobilization kinetics wereinvestigated, and a significant increase in the yield was obtained after immobilization compared with that obtained from assay 8 (22.0 U mL −1 vs. 15.6 U mL −1). The enzyme efficiency of actuation was evaluated using o -nitrophenyl-B-d-galactopyranoside and lactose, with lactose providing better results. The reuse of B-galactosidase was evaluated, and more than 50% of the initial enzyme activity was maintained after five cycles of use. Enzyme characterization revealed that immobilization improved some aspects of the thermostability of B-galactosidase.