Enzyme Immobilization by Ethylene-Vinylalcohol Copolymer Entrapment : The Effects of Coimmobilization of Fine Particles

In order to elucidate the effects of the presence of a particle within an immobilized enzyme, β-glucosidase (β-GD) and a fine particle such as silicon, γ-alumina and hydroxyapatite has been coimmbilized in ethylene-vinylalcohol copolymer (EVA) membrane. The coimmobilized β-GD was characterized enzymatically compared with native enzyme, using p-nitrophenyl-β-D-glucopyranoside (PNPG) as a substrate. Diffusion and partiton coefficients (D and P, respectively) of PNPG and reaction products in EVA membrane with and without particles were determined by a conventional method. Apparent affinity for the substrate increased by the presence of a particle. Enzyme affinity for substrate in the EVA membrance was discussed on the basis of the data of D, P, membrance thickness and kinetic parameters.