咪唑/吡啶离子液体辅助氯过氧化物酶催化氧化环己烯的研究

Studies on the Oxidation of Cyclohexene Catalyzed by Chloroper-oxidase in the Presence of Imidazole/pyridine Ionic Liquids

以氯过氧化物酶(CPO)催化、H2O2氧化实现环己烯的环境友好转化,并通过溶剂工程调控和提高目标产物的产率.研究结果表明缓冲液体系(PBS)中引入咪唑/吡啶类离子液体(ILs)时,含量仅为1.5%(WILs/WPBS)时环己烯转化率即可提高31%.酶促反应动力学参数Km的减小以及Kcat和Kcat/Km的增大表明引入离子液体时CPO对底物的亲和力及对底物识别的专一性得以改善,导致转化数增大,这是底物转化率有效提高的主要原因;此外,紫外,荧光及圆二色谱研究及产物组成分析表明离子液体在反应体系中具有多重功能:相转移催化、诱导酶分子结构优化及调节产物组成.由于反应基本在150 min内结束,酶用量极少,因此具有一定的产业化应用潜能.

The environmental friendly biotransformation of cyclohexene catalyzed by chloroperoxidase（CPO） with H2O2 as oxidant was carried out in this work.The yield of expected products was tuned and en-hanced by solvent engineering.The results showed that the conversion of cyclohexene was enhanced 31% when only 1.5%（WILs/WPBS） of imidazole/pyridine ionic liquids（ILs） was introduced into the PBS buffer.The decrease of enzyme kinetic parameters Km and increase of Kcat and Kcat/Km indicated that both the affin-ity and specificity of CPO to the substrate were improved in the presence of ILs,resulting in the increase of turnover number.This was the main reason of conversion enhancement.Moreover,UV-vis,fluorescence and circular dichroism assay and analysis of products composition indicated that ILs played multiple func-tions in this enzyme-catalyzed reaction： phase transfer catalysis,inducing catalytically favorable conforma-tion of CPO and tuning the composition of products.This enzymic-reaction was over within 150 min,and enzyme consumption was small.So,it has some potential utility in industry application.