| The immobilized enzyme is being widely and profoundly studied because it has more advantages, such as more stabilization,more times of use and more easiness of separating product from substrate. At present the central problem is how to prepare and choose carrier and how to improve the properties of the immobilized enzyme. The biofunctional magetic polymer material is a fringe field between the science of polymer and biology, which has lots of especial superiority as the support of immobilized enzyme.A novel kind of hydrophilic porous magnetic microspheres with a narrow size distribution and rich epoxy groups were synthesized by using suspension polymerization in the presence of poromeric agents from glycidyl methacrylate and ethylene dimethacrylate with surface-modified superparamagnetic nanoparticles embedded. On the microspheres papains were immobilized as the optimum conditions and the immobilized enzymes of high activity and excellent properties were obtained. Furthermore, the catalytic function of papains was not impaired significantly by its immobilization. Meanwhile using casein as substrate, the properties and dynamical parameters of immobilized papain were determined: the optimum reactive temperature 80℃, pH 7.5 and K_m 4.25 mg/mL, respectively. The recovery activity of immobilized enzyme was still retained 55.2%.Especially the thermal stabilization, pH and operational stabilization of the immobilized enzyme were greatly improved in comparison with free ones. The magnetic polymer microspheres were also modified with flexible and hydrophilic DAS. After being bound with papain we obtained the immobilized enzyme. All the results showed that the enzyme recovery increased greatly with amount of added enzyme decreasing, and K_m also reduced, which illustrate that the enzyme affinity to substrate improved.The kind of magntic polymer microspheres should be a excellent immobilized support, and has much application in the related biomedical industry.
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