Two new ultrafiltration membranes were obtained from a polymer mixture, containing 60% polyacrylonitrile (PAN) and 40% copolymer of methylmethacrylatedichlorophenylmaleimide (MMA-DCPMI). Membrane 1 (MBI) contains 40% DCPMI of the copolymer, and membrane 2 (MB2) contains 1.5% of the copolymer. The pore size, the specific surface, the water content, the water flux, and the selectivity were determined for the two membranes. The presence of dichlorophenylmaleimide in the copolymer ensures the preparation of membranes suitable for direct covalent enzyme immobilization without further modifications. These membranes were used for immobilization of glucose oxidase (GOD). High amount of bound protein was found on each of the membranes. High relative activities of the immobilized GOD were achieved, 72% for MB1 and 68% for MB2. The properties of the immobilized enzyme (GOD) were determined: optimum pH and temperature and pH, thermal, and storage stability, and then compared with the properties of the native enzyme. The kinetic parameters of the enzyme reaction, Michaelis constant (K) and maximum reaction rate (V-max), were also investigated. The results obtained showed that the ultrafiltration membranes prepared from the mixture of PAN and the copolymer MMA-DCPMI were suitable for use as carriers for the immobilization of GOD. (c) 2006 Wiley Periodicals, Inc.