硅烷化氨基磁性粒子的制备及其固定化木瓜蛋白酶的研究

通过硅烷化试剂(3-氨基丙基三乙氧基硅烷)对SiO2包覆的Fe3O4磁性纳米粒子进行表面修饰,得到了一种高亲水性、粒度均匀、表面富含氨基的磁性复合粒子,并以木瓜蛋白酶为模式酶,探讨了木瓜蛋白酶的最佳固定化条件,研究了固定化木瓜蛋白酶的酶学性质和动力学参数。结果表明:当戊二醛浓度在5%,固定化时间为4h,给酶量为10mg/g时,固定化酶的酶活最高;固定化酶的最适反应温度为70℃,最适反应pH值为6.8,Km值为34.48mg/mL,酶活回收率为46.5%。固定化酶在热稳定性和pH稳定性上较游离酶均得到了一定的提高。

Preparation of Amino Group Coated Magnetic Microspheres by Silanization and its Study on Immobilizing Papain

Magnetite nanoparticles were prepared by coprecipitation of Fe2+ and Fe3+ with NH4OH,and then,silica was coated on the surface of the magnetite nanoparticles to form hydrophilic,well-distributed and well-dispersed magnetic silica nanospheres.Amino-silane was covalently coupled to the surface of the magnetic silica nanospheres and activated by glutaraldehyde.The immobilization of papain on the particles was studied,including optimization of immobilizing procedures,analysis of the immobilizing enzyme properties and its kinetics parameters.Results showed that immobilized enzyme has its optimizing temperature and pH at 70 ℃ and 6.8,respectively.Its Km was 34.48 mg/mL,and the enzyme activity reached 46.5%.It was proved that the amino-silane treated magnetic silica nanospheres could enhance the thermo stability,the pH endurance and the operation time of the enzyme compared to free enzyme.