摘要
采用疏水性离子液体1-丁基-3-甲基咪唑六氟磷酸盐([BMIM]PF6)与缓冲液构成的两相体系,在其中进行了膜醭毕赤酵母(Pichia membranaefaciens Hansen)细胞催化乙酰乙酸乙酯(EOB)不对称还原,制备光学活性的(R)-3-羟基丁酸乙酯(R-EHB)。系统地考察了一些因素,如离子液体浓度、缓冲液pH、辅助底物种类和浓度、反应温度、底物浓度、菌体浓度和转化时间等对该反应的影响。结果表明,上述因素对反应的产率和产物光学纯度影响较大。较佳的生物还原反应条件为:[BMIM]PF6体积分数20%,辅助底物为80g·L-1葡萄糖,pH7.8,反应温度30℃,底物乙酰乙酸乙酯浓度0.5mol·L-1,菌体浓度280g·L-1,转化18h。在此优化条件下,反应产率达72.2%,R-EHB对映体过量值为70.3%。与单一水相体系和正己烷-缓冲液两相体系相比较,在[BMIM]PF6-缓冲液两相体系中进行EOB的生物不对称还原可有效减少底物抑制,提高反应效率。
A hydrophobic ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate （[BMIM]PF6） was used as the solvent for asymmetric bioreduction of ethyl acetoacetate （EOB） to prepare optically active ethyl （R）-3-hydroxybutyrate （R-EHB） with Pichia membranaefaciens Hansen cells. The suitable reaction conditions, such as [BMIM]PF6 content, pH value, co-substrate concentration, reaction temperature, substrate concentration, cell concentration and reaction time, were investigated, respectively. The results show that these factors obviously influence the yield and the optical purity of the prepared R-EHB. The optimum values of [BMIM]PF6 content, pH value, co-substrate concentration, reaction temperature, substrate concentration, cell concentration and reaction time are 20 %, 7.8, 80 g.L^-1, 30℃, 0.5 moI.L^-1, 280 g.L^-1 and 18 h, respectively. Under above optimal conditions, the maximum yield of 72.2 % and 70.3 % of e.e. of the prepared product were obtained, respectively. The results also demonstrate that the inhibition effect of EOB on R-EHB yield can be markedly reduced by the use of [BMIM]PF6 and the bioconversion is more efficient in [BMIM]PF6-buffer biphasic system than that in monophasic aqueous system or hexane-buffer biphasic system.
出处
《高校化学工程学报》
EI
CAS
CSCD
北大核心
2008年第5期833-838,共6页
Journal of Chemical Engineering of Chinese Universities
基金
浙江省科技厅重大科技项目资助(2005C13024)
浙江省自然科学基金项目资助(Y407289)
