含环氧基亲水性固定化青霉素酰化酶共聚载体的合成与性能研究

环氧基团可以在温和条件下与酶分子的氨基反应使其固定于载体表面.选用含有活性环氧基团的甲基丙烯酸缩水甘油酯(GMA)和亲水性的N-乙烯吡咯烷酮(NVP)两种单体,以N,N′-亚甲基双丙烯酰胺(MBAA)为交联剂,甲醇水溶液作致孔剂,液体石蜡为主介质,通过反相悬浮聚合技术成功地合成了亲水性大孔GMA-NVP-MBAA三元共聚物载体(GNM).通过调节交联剂的用量和单体NVP与GMA的比例,可以调节载体的孔径、比表面积及在水中的溶胀性能.将巨大芽孢杆菌青霉素酰化酶共价偶联于平均孔径为16.5nm、表面环氧基含量为0.906mmol/g的GNM共聚物载体,制成固定化酰化酶,其表观活性高达625U/g,水解青霉素G钾盐的最适宜温度为50℃,pH值为8.0.固定化酶在4℃保存40d,活性保持不变.经3次使用后,活性达到稳定值(601U/g左右),再经12次使用,活性几乎保持不变.

Synthesis and Properties of the Hydrophilic Copolymer Support Containing Oxirane for Immobilized Penicillin Acylase

Oxirane groups can react with the amino groups of enzyme under mild conditions so that the enzyme molecules are immobilized on the copolymer support containing oxirane. A series of macroporous hydrophilic copolymers(GNM) containing oxirane were synthesized by inverse suspension polymerization with glycidyl methacrylate(GMA) as the reactive monomer, N-vinyl-2-pyrrolidone(NVP) as the hydrophilic comonomer, N,N′-methylene-bis-acrylamide(MBAA) as the crosslinking agent, and methanol and water as the porogenic agent and used as the support for the immobilization of penicillin G acylase(PA). The effects of the amount of the crosslinking agent on the structure properties and the apparent activity of immobilized enzyme were investigated. The specific surface area of GNM copolymer increased, its average pore diameter and pore volume decreased, and swelling degree in water increased and then decreased with increasing the amount of the crosslinking agent. The apparent activity of 625 U/g(dry weight) was obtained when the enzyme immobilized on GNM polymer m(NVP)/m(GMA)=1/5, {w(MABB)=}40%] with a mean pore diameter of 16.5 nm, an oxirane group content of 0.906 mmol/g and swelling degree of 203% in water. The optimal pH value and temperature of the hydrolysis of penicillin G over the immobilized enzyme was 8.0 and 50 ℃, respectively. The immobilized enzyme was kept at 4 ℃ for 40 d, the change of the activity was not observed.The apparent activity of the immobilized enzyme reached a relatively steady value(about 601 U/g) after the immobilized enzyme was used for the hydrolysis of penicillin G for 3 times at 37 ℃. It was used continuously and repeatedly for 12 times, the activity was hardly changed.