多孔磁性微球固定化PGA催化合成头孢氨苄的性能研究

Synthesis of cephalexin by immobilized PGA on porous magnetic polymer microspheres

采用反相悬浮技术,由Fe_3O_4磁粉、甲基丙烯酸缩水甘油酯(GMA)、N,N'-亚甲基双丙烯酰胺(MBAA)制备磁性聚合物微球Fe_3O_4@GM,用磁性微球固定化青霉素酰化酶,在甲醇-磷酸盐缓冲溶液中催化7-氨基-3-脱乙酰氧基头孢烷酸(7-ADCA)与D-苯甘氨酸甲酯(D-PGM)反应合成头孢氨苄,研究了甲醇浓度、7-ADCA与D-PGM摩尔比和反应温度及时间等因素对磁性固定化酶催化合成头孢氨苄性能的影响。结果表明,最佳工艺条件为:溶剂中甲醇含量为40%(v/v),底物7-ADCA与D-PGM浓度分别为60 mmol/L和180 mmol/L(二者摩尔比1∶3),10℃下反应4 h,此时头孢氨苄产率达到72.1%,合成与水解比S/H为1.2;在相同反应条件下,使用游离青霉素酰化酶,二者分别为52.0%和0.7,表明青霉素G酰化酶经多孔磁性微球固定化后,催化活性和选择性得到明显提高。

Fe3O4,GMA and MBAA to prepare Fe3O4@ GM by inverse suspension polymerization. The penicillin G acylase（ PGA） immobilized on the magnetic microspheres gives efficient catalyst for synthesis of cephalexin from 7-amino-3-desacetoxicephalosporanic acid（7-ADCA） and D-phenylglycine methyl ester（ D-PGM） in methanol-phosphate buffer solvent. The effects of 7-ADCA and D-PGM concentration,molar ratio of 7-ADCA to D-PGM,reaction temperature,and solvent pH on catalytic performance of the magnetic immobilized PGA for synthesis of cephalexin were studied. The result showed that the reaction conditions were optimized as following：the methanol content of 40%（ v/v）,60 mmol/L 7-ADCA,180 mmol/L D-PGM（ D-PGM to 7-ADCA molar ratio of 3 ∶ 1）,reaction temperature 10 ℃,reaction time 4 h and pH 7. 6. The yield of cephalexin reached 72. 1% and the molar ratio of synthesis to hydrolysis S/H of1. 2. While using free penicillin G acylase under the same reaction conditions,the yield of cephalexin and S/H value was 52. 0% and 0. 7,respectively,which indicated that the catalytic activity and selectivity of penicillin G acylase were improved after the immobilization on the porous magnetic microspheres.