固定化青霉素酰化酶在光敏感可再生两水相体系中催化青霉素G为6-APA  

Phase Transfer Bioconversion of Penicillin G into 6-APA by Immobilized Penicillin Acylase in Recycling Aqueous Two-Phase Systems with a Light-Sensitive Copolymer

作　　者：金科铭[1] 曹学君[1] 庄英萍[1] 储炬[1] 张嗣良[1] Orawan Duerasor 

机构地区：[1]华东理工大学生物反应器工程国家重点实验室 [2]Department of Biotechnology Faculty of Science,Mahidol University,Bangkok 10120,Thailand

出　　处：《华东理工大学学报（自然科学版）》2007年第3期318-322,共5页Journal of East China University of Science and Technology

基　　金：国家自然科学基金资助项目(20474016)

摘　　要：在一种光敏感可再生高聚物（PNBC 300000）与葡聚糖20000（Dextran 20000）形成的两水相体系中进行固定化青霉素酰化酶的相转移催化青霉素G产生6-APA的反应。在这个两水相体系中,当pH为7.8,底物浓度为62 mmol/L,反应温度为20℃,在50 mmol/L KCl存在下,6-APA的分配系数可达8.4。催化动力学显示,达到平衡的时间近6 h,PG（Na）转化率约82.6%。3批半连续反应转化率为60%~70%,较相近条件下的单水相反应得率提高近20%。在两水相中,底物及产物主要分配在上相,固定化酶分配在下相,底物青霉素G进入下相经酶催化产生的6-APA及苯乙酸又转入上相,从而解除了青霉素酰化酶催化反应的底物及产物抑制作用,达到提高产物得率的效果。形成两水相的高聚物通过488 nm的激光照射可实现循环利用,高聚物的光照回收率在95%~98%。Immobilized penicillin acylase was used for bioconversion of penicillin G into 6-APA in aqueous two-phase systems consisted of a light-sensitive polymer （PNBC300000） and Dextran 20000. Partition coefficients of 6-APA was found to be about 8.4 in the presence of 50 mmol/L KCl. Results of enzyme kinetic studies showed that the reaction reached equilibrium at 6 h or so. The conversion ratio of PG（Na） were 82.6 % （pH 7.8, 2.2 % substrate concentration and 20 ℃ ）, which was about 20 % higher than that of out. In aqueous two-phase systems, substrate penicil lin G, products 6-APA and phenylacetate acid are biased in top phase, while immobilized penicillin acylase is completely partitioned in bottom. Substrate penicillin G entering into bottom phase, is catalyzed to 6-APA and phenylacetate acid, then the products diffused into top phase. Finally, inhibition of substrate and products was removed which led to the in improvement of products yield. Moreover, immobilized enzyme has higher efficiency than immobilized cells and occupy smaller volume. Comparing with free enzyme, immobilized enzyme has higher stability, longer working life, completely partitioned in bottom phase and the capacity of recycling. Bioconversion in two-phase systems using immobilized penicillin acylase showed outstanding advantage. The light-sensitive copolymer forming aqueous two-phase systems could be reused by laser radiation at 488 nm, with the recovery of 95%-98%.

关 键 词：可再生两水相 光敏感聚合物 青霉素G 6-APA 固定化酶青霉素酰化酶 

分 类 号：Q814.3[生物学—生物工程]