含氨基和环氧基双功能基的聚合物刷磁性微球的制备及对青霉素G酰化酶的固定化

在内部分散超顺磁性Fe3O4纳米粒子的二乙烯苯交联聚丙烯酸微球表面引入原子转移自由基聚合(ATRP)引发剂,引发聚合向微球表面分别引入P(GMMA-r-DMAEMA-r-GMA)、P(GMMA-r-DMAEMA)和P(GMMA-r-GMA)无规共聚物刷(GMMA为甲基丙烯酸甘油单酯,DMAEMA为甲基丙烯酸-N,N-二甲氨基乙酯,GMA为甲基丙烯酸缩水甘油酯),聚合物刷中GMMA链节的作用是使聚合物刷具有亲水性,DMAEMA引入氨基,GMA引入环氧基.研究了青霉素G酰化酶在这些载体上的固定化和其酶活性.结果表明,同时引入环氧基和氨基的P(GMMA-r-DMAEMA-r-GMA)刷磁性微球固定化青霉素G酰化酶的活性和活性收率都最高,其固定化动力学比只含环氧基P(GMMA-r-GMA)刷磁性微球的好.固定化酶比自由酶更耐热,固定化酶的最佳pH值比自由酶的略高,固定化酶重复使用10次后其活性保留70%.

PREPARATION OF MAGNETIC MICROSPHERES WITH POLYMER BRUSHES CONTAINING EPOXIDE AND AMINO GROUPS AND IMMOBILIZATION OF PENICILLIN G ACYLASE ON THEM

Magnetic microspheres with polymer brushes containing epoxide and amino groups were prepared and used as the support for immobilization of penicillin G acylase.The introduction of the amino group would accelerate the adsorption of enzyme to the support by ionic interaction,and then the adsorbed enzyme was immobilized covalently by reacting with the epoxide group.Magnetic microspheres with atom transfer radical polymerization(ATRP)initiators were first prepared from crosslinked poly(acrylic acid)microspheres in which superparamagnetic Fe_3O_4 nanoparticles were dispersed.Random copolymer P(GMMA-r-DMAEMA-r-GMA)(GMMA,glycerol monomethacrylate,DMAEMA,N,N-dimethylamino)ethyl methacrylate,GMA,glycidyl methacrylate)was grafted onto the magnetic microspheres by ATRP initiated from the magnetic microsphere initiators.For comparison,magnetic microspheres with P(GMMA-r-DMAEMA)or P(GMMA-r-GMA)brushes were also prepared.The GMMA units in the brushes made the brushes to be hydrophilic;DMAEMA units introduced amine groups and GMA units introduced epoxide groups.Immobilization of penicillin G acylase on these brush-grafted magnetic microspheres showed that both of the activity and activity yield of immobilized penicillin G acylase on P(GMMA-r-DMAEMA-r-GMA)brush-grafted magnetic microspheres were the highest,and the immobilization on them was faster than that on P(GMMA-r-GMA)brush-grafted magnetic microspheres.The immobilized enzyme possessed much higher thermal stability than the free enzyme.The optimal pH value for the immobilized enzyme was slightly higher.After ten cycles of repeated use,70% of the activity still remained.