【摘要】 利用反相悬浮交联法制备磁性壳聚糖微球(magneticchitosanmicrospheres,M-CS),并对褐藻酸酶进行固定化研究。结果表明,M-CS呈规则的圆球形,具有较好的磁响应性,可稳定地保存在弱酸和弱碱中。其弱碱交换量随着戊二醛用量的增加而减少,悬挂醛基则相应地增加。M-CS对褐藻酸酶的吸附动力学实验表明,M-CS容易吸附褐藻酸酶,但吸附的酶量受载体与酶的比例、溶液的离子浓度、戊二醛的用量、溶液pH的影响明显,而温度对吸附的酶量的影响则相对较弱。酶学性质研究表明,相对于游离的褐藻酸酶,固定化酶的最适温度略有升高,可明显改善其热稳定性和酸碱稳定性,与底物的亲和力也有所增强。更多还原

【Abstract】 Some researches on magnetic chitosa microsphere（M-CS）have been studied on its preparation and the influence factors during the preparing process, as well as the equilibrium and kinetic modeling of absorption of reactive dye on cross-linded chitosan beads. In this experiment, the M-CS was prepared by reverse-phase suspension cross-linking, and used to immobilize the alginate lyase. Under scan microscope, the M-CS shows regular spheroid. It had magnetic response characteristic, and was stable in weak basic and weak acid solutions. The weak basic exchange capacity was reduced with the increasing of the glutaraldehyde amount, but the hanging aldehyde group ability was accordingly increased. Fe₃O₄ in M-CS was easily decompounded, and M-CS lost the magnetism in acid solution, therefore the stability of M-CS in solution was important for its application. The M-CS suspended in H₂O solution was easily precipitated and separated by magnetic field. Mechanical strength and crosslinking degree of M-CS were influenced by the amount of pentanedia, and eventuated in different activity of immobilized alginate lyase. The amount of alginate lyase immobilized in M-CS reached 40% with 0.25 mg/mL concentration of the lyase in solution. The amount of alginate lyase immobilized in M-CS gradually decreased with the increase of ion strength in buffer. The immobilization of alginate lyase by M-CS depended on neutral buffer. The immobilization was slightly influenced by the reaction temperature. The suitable temperature of immobilized alginate lyase was 45-50 ℃, and the suitable pH of immobilized alginate lyase was 7.0. The immobilization would improve its thermal, and basic-resistant, and acid-resistant stability. It would enhance its appetency for the substrate.The adsorptive isothermal measurement indicated the adsorptive isothermal equation was as following: lgQ=0.960+0.169lgC. Therefore, the alginate lyase was easily immobilized by M-CS. The adsorption kinetics of the alginate lyase on M-CS indicated that the adsorption of the alginate lyase on M-CS was easy, but the adsorption affinity was defected by the amount ratio of the carrier to the enzyme. It was showed the K_m was 0.018 9 mg/mL and 0.013 35 mg/mL in in free enzyme and immobilized enzyme, respectively. The most reactive rate were 0.258 UA/min and 0.121 0 UA/min in free enzyme and immobilized enzyme, respectively.更多还原