Immobilization of lipase with a special microstructure in composite hydrophilic CA/hydrophobic PTFE membrane for the chiral separation of racemic ibuprofen
Immobilization of lipase with a special microstructure in composite hydrophilic CA/hydrophobic PTFE membrane for the chiral separation of racemic ibuprofen
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DOI：
10.1016/j.memsci.2007.02.006
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发表时间：
2007-04
影响因子：
9.5
通讯作者：
Yujun Wang;Y. Hu;Jian Xu;G. Luo;You-yuan Dai
中科院分区：
文献类型：
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作者：
Yujun Wang;Y. Hu;Jian Xu;G. Luo;You-yuan Dai
脂肪酶催化布洛芬酯的不对称水解反应是布洛芬手性拆分的重要方法之一。本研究设计了一种特殊的亲水性醋酸纤维素（CA）/疏水性聚四氟乙烯（PTFE）复合膜微结构，用于超滤固定化脂肪酶。采用两相酶膜反应器（EMR）和含游离脂肪酶的乳液反应体系，比较了固定化酶和游离酶的活性、对映体选择性和半衰期。通过扫描电镜（SEM）观察了复合膜的形貌及包埋物在固定化脂肪酶复合膜微结构中的位置。考察了底物浓度、酶用量、反应温度和pH对分离的影响。实验结果表明，脂肪酶被截留在复合膜的界面处，这与水相和有机相的界面相一致。由于固定化酶不破坏酶的结构，因此保持了较高的酶活，当酶负载量低于1g蛋白/m2时，酶活比游离脂肪酶提高了60%以上。同时，固定化酶具有更好的手性选择性（最高可达83.5%eep）和更长的半衰期（约183.3h，而其他研究者报道的为94 h）。当底物浓度为0.35M，酶载量为0.7- 1.0g-蛋白/m2，水相pH8.0，温度为40 ℃时，可获得较高的酶活和手性选择性。
The asymmetric hydrolyzation of racemic ibuprofen ester catalyzed by lipase is one of the most important methods for the chiral separation of ibuprofen. In this work, a special microstructure in the composite hydrophilic cellulose acetate (CA)/hydrophobic polytetrafluoroethylene (PTFE) membrane was designed for lipase immobilization by ultrafiltration. A biphasic enzymatic membrane reactor (EMR) and an emulsion reaction system with free lipase were both used, and the activity, enantioselectivity selectivity and half-life of immobilized and free enzymes were compared. The morphology of the composite membrane and the position of the entrapment in the microstructure of composite membrane where lipase were immobilized were observed by scanning electron microscopy (SEM). The effects of substrate concentration, enzyme loading, reaction temperature and pH on the separation were investigated. The experimental results showed that the lipase was entrapped at the interface of the composite membrane, which is consistent with the interface of aqueous phase and organic phase. Because the immobilized enzyme by our new method did not destroy the enzyme structure, it retained higher activity; the enzyme activity was more than 60% compared to the free lipase when enzyme loading was under 1g-protein/m2. Meanwhile, the immobilized enzyme provided better chiral selectivity (up to 83.5% eep) and a longer half-life (about 183.3h in our work compared to 94h as reported by other researcher). High enzyme activity and chiral selectivity were obtained with a substrate concentration of 0.35M, enzyme loading of 0.7–1.0g-protein/m2at aqueous phase pH 8.0 and a temperature of 40°C.