中国生物工程杂志

The SMA modified PVDF membrane were prepared by the copolymerization of styrene with maleic anhydride on the surface of PVDF membrane in the supercritical carbon dioxide. Free β-galactosidase was immobilized on the membranes by the formation of amido bonds between the amino groups of the enzyme and the anhydrides on the surface of the membranes. The effects of immobilization on the properties of the immobilized β-galactosidase were studied. The immobilized membrane showed the highest activity when β-galactosidase was immobilized for 6h under the condition of pH 8.2, 4 C, and enzyme/membrane 1:10. The activity of immobilized enzyme and protein binding capacity reached 13.5U and 68.2 g/cm2 membrane. The specific activity of immobilized enzyme could reach 280.0U/mg protein. The relative activity was 89.0%, compared with the free β-galactosidase. The immobilized enzyme had higher optimum temperature（55oC） and pH（7.8） compared with that of free β-galactosidase and showed excellent operational and storage stability.