Simultaneous covalent immobilization of glucose oxidase and catalase onto chemically modified acrylonitrile copolymer membranes

Abstract

Abstract Ultrafiltration membranes from acrylonitrile copolymer were chemically modified with different concentrations of hydrogen peroxide (from 5 to 30% H 2 O 2 ). The amount of the amide groups in the modified membranes was determined. The water flow and permeability coefficients of the initial and modified membranes were also researched. The modified membranes were used as carriers for covalent immobilization of the dual enzyme system of glucose oxidase and catalase (GOD+CAT). It was found that the best matrices for immobilization of the dual system were membranes modified with 20% H 2 O 2 and the optimal activity ratio was GOD : CAT = 1 : 5. The glucose conversion efficiency with the dual enzyme system was twice as high as that of bound GOD alone. Some of the basic characteristics (optimum pH, optimum temperature, pH, temperature stability, and storage stability) of the dual enzyme system were determined and compared with characteristics of free and bound enzymes. The catalytic parameters of the enzyme reaction ( K m and V max ) were determined with GOD immobilized alone and with the dual system GOD+CAT. The higher rate observed with the dual enzyme system clearly showed the advantage and the efficiency of the immobilized system. Glucose oxidase without catalase was deactivated by H 2 O 2 more rapidly than the immobilized dual GOD+CAT system. These experimental evidences can be explained by the protecting effect of catalase on glucose oxidase from inhibition by H 2 O 2 . © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 4057–4063, 2004