催化学报

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青霉素G酰化酶在含环氧基团的顺磁性聚合物微球上的固定化

陈星, 杨露, 詹望成, 王丽, 郭耘, 王筠松, 卢冠忠, 郭杨龙   

  1. 华东理工大学工业催化研究所, 上海 200237
  • 收稿日期:2017-08-22 修回日期:2017-10-13 出版日期:2018-01-18 发布日期:2018-01-19
  • 通讯作者: 詹望成, 郭杨龙
  • 基金资助:

    国家自然科学基金(91545103);上海市曙光计划(10SG30);中央高校基本科研业务费专项资金(222201717003).

Immobilization of penicillin G acylase on paramagnetic polymer microspheres with epoxy groups

Xing Chen, Lu Yang, Wangcheng Zhan, Li Wang, Yun Guo, Yunsong Wang, Guanzhong Lu, Yanglong Guo   

  1. Key Laboratory for Advanced Materials and Research Institute of Industrial Catalysis, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
  • Received:2017-08-22 Revised:2017-10-13 Online:2018-01-18 Published:2018-01-19
  • Contact: 10.1016/S1872-2067(17)62934-6
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (91545103), Shu Guang Project of Shanghai Municipal Education Commission and Shanghai Education Development Foundation (10SG30), and the Fundamental Research Funds for the Central Universities (222201717003).

摘要:

青霉素G酰化酶(PGA)是一种重要的工业生物催化剂,常用于以青霉素G为底物生产7-氨基去乙酰氧基头孢烷酸(7-ADCA)和6-氨基青霉烷酸(6-APA)等半合成β-内酰胺类抗生素.然而,PGA较差的稳定性和可重复使用性能限制了其在工业上的广泛应用.因此,将PGA固定在固体载体上是很有必要的,可以形成一种可重复使用的高性能的多相催化剂.用于生物酶固定化的良好载体应具备以下条件:(1)载体表面具有可用于与生物酶多点结合的高密度的官能团;(2)载体具有较大的比表面积以固定更多的生物酶.通常情况下,可以通过减小载体的粒径来增加其比表面积,然而,小粒径的载体很难从反应混合液中分离出来,造成固定化酶回收使用困难.为了将聚合物微球的优异固定化性能与磁性纳米粒子的独特顺磁性结合起来,我们制备了一种含环氧基团的顺磁性聚合物微球作为PGA的固定化载体.但由于Fe3O4纳米颗粒具有较高的表面能,在反相悬浮聚合反应过程中容易团聚成大颗粒,从而导致制备的顺磁性聚合物微球的磁体含量、表面形貌和粒径分布存在差异.此外,Fe3O4纳米颗粒与聚合反应单体之间的相容性不好,使得部分磁性颗粒不能很好地包埋于聚合物微球内部,影响固定化酶的活性和操作稳定性.本文以N,Nx-亚甲基双丙烯酰胺为交联剂,以甲基丙烯酸缩水甘油酯和烯丙基缩水甘油醚为功能性单体,用反相悬浮聚合方法在SiO2包覆的Fe3O4纳米颗粒表面成功制备出含环氧基团的顺磁性聚合物微球.用SEM,FT-IR,XRD,VSM和低温氮气吸附等手段对含环氧基团的顺磁性聚合物微球进行了表征.研究了SiO2对Fe3O4纳米颗粒的包覆和Fe3O4/SiO2纳米颗粒的数量对于固定化酶的初始活性和操作稳定性的影响.SiO2在反相悬浮聚合过程中发挥重要作用,用SiO2对Fe3O4纳米颗粒进行亲水性改性,有效改善了Fe3O4纳米颗粒与聚合反应单体的相容性,将其引入反相悬浮聚合体系中,可以制备得到球形度好、粒径分布均匀和超顺磁性的含环氧基团的顺磁性聚合物微球,其中当Fe3O4/SiO2纳米颗粒的质量比为7.5%时制备的含环氧基团的顺磁性聚合物微球具有最好的PGA固定化性能.PGA通过其活性非必需侧链基团-氨基与顺磁性聚合物微球表面的环氧基团的共价结合来制备顺磁性固定化酶,该固定化PGA的初始活性为430 U/g (wet),在外加磁场的作用下容易回收使用,重复使用10次后可保留99%的初始活性,具有良好的热稳定性和酸碱稳定性,具有较好的工业应用前景.

关键词: 顺磁性聚合物微球, 环氧基团, 青霉素G酰化酶, 共价结合, 固定化

Abstract:

Paramagnetic polymer microspheres were synthesized by the inverse suspension polymerization method through polymerization of glycidyl methacrylate, ally glycidyl ether and methacrylamide on the surface of silica-coated Fe3O4 nanoparticles using N,N'-methylene-bis(acrylamide) as a cross-linking agent. Penicillin G acylase (PGA) was covalently immobilized on the surface of the paramagnetic microspheres by reacting the amino groups of the PGA molecules with the epoxy groups of the paramagnetic polymer microspheres. The effect of the SiO2 coating and the amount of paramagnetic Fe3O4 nanoparticles on the initial activity and the operational stability of the immobilized PGA was investigated. The results indicated that SiO2 played an important role in the polymerization process and paramagnetic polymer microspheres with a SiO2-coated Fe3O4 nanoparticles mass content of 7.5% are an optimal support material for PGA immobilization. Immobilized PGA on the paramagnetic polymer microspheres shows a high initial activity of 430 U/g (wet) and retains 99% of its initial activity after recycling 10 times. Furthermore, immobilized PGA exhibits high thermal stability, pH stability and excellent reusability, which can be rapidly recycled by the aid of magnet.

Key words: Paramagnetic polymer microspheres, Epoxy groups, Penicillin G acylase, Covalent bonding, Immobilization