Abstract:

Polyethyleneimine (PEI) flocculation and glutaraldehyde (GA) crosslinking were used to prepare crosslinked cell aggregates (CLCAs) of whole cells of epoxide hydrolase. The effects of PEI concentration, GA concentration and diatomite carrier dosage on the activity recovery of CLCAs were investigated, the results show that the optimal values of PEI concentration, GA concentration and diatomite carrier dosage are 3% (vol), 1% (vol) and 6 g/L, respectively and activity recovery reached 88.4%. Using CLCAs as catalysts, racemic epichlorohydrin ((R,S)-ECH) as substrate, the synthesis of (R)-epichlorohydrin ((R)-ECH) in isooctane / phosphate buffer biphase system was investigated. The results show that under the condition of 3∶7 volume ratio of isooctane to buffer, substrate concentration 800 mmol/L, addition of CLCAs 18 g/L, buffer pH 8.0, temperature 35℃, the molar yield of (R)-ECH reached 45.2%, with 99.1% ee. The operational stability of CLCAs in the two-phase system was investigated, and the viability of 9 batches reused remained basically unchanged, showing good operation stability.

Key words: epoxide hydrolase, cross-linked cell aggregates, immobilization, biocatalysis, multiphase reaction, chiral epichlorohydrin

摘要：

利用聚乙烯亚胺(PEI) 絮凝、戊二醛(GA)交联对环氧化物水解酶全细胞进行了交联细胞聚集体(CLCAs)制备，考察了PEI浓度、GA浓度及硅藻土载体用量对CLCAs活力回收率的影响，结果表明PEI浓度、GA浓度及硅藻土载体用量最优值分别为3% (体积)和1%(体积)和6 g/L，此时CLCAs活力回收率可达88.4%。以CLCAs作为催化剂，以外消旋环氧氯丙烷((R,S)-ECH) 为底物，在异辛烷/磷酸盐缓冲液两相体系中催化合成(R)-环氧氯丙烷((R)-ECH)。结果表明，在异辛烷与缓冲液的体积比3∶7，底物浓度800 mmol/L，CLCAs加入量18 g /L，缓冲液pH 8.0，温度35℃条件下，(R)-环氧氯丙烷的摩尔产率达到45.2%，产物光学纯度为99.1% ee。考察了CLCAs在两相体系中的操作稳定性，重复使用9个批次活力基本保持不变，显示了良好的操作稳定性。

关键词: 环氧化物水解酶, 交联细胞聚集体, 固定化, 生物催化, 多相反应, 手性环氧氯丙烷