Immobilization of β-glucosidase by Radiation-polymerization

Abstract

Almond β-glucosidase was immobilized by a radiation-polymerization method in a frozen state. The most suitable monomers to give highest activity retention (72%) were polyvinyl alcohol and magnesium acrylate with N, N'-methylene bis acrylamide. No leakage of β-glucosidase from the polymer matrix was observed. Compared with free β-glucosidase, the immobilizen enzyme exhibited (1) improved stability at the acetate buffer concentration of 20-40mM. (2) pH optimum shifted to 4.5 from 5.2 and improved stability at lower and higher pH. (3) A similar optimum reaction temperature, 55°C, but improved thermalstability. (4) Higher apparent Km (20.8mM) for cellobiose compared with Km (5.6mM) of free enzyme.