吐温/缓冲液体系中酶法合成 (R)-对氯环氧苯乙烷

Enzymatic synthesis of (R)-p-chlorostyrene oxide in tween/buffer system

摘要:

利用环氧化物水解酶突变体PvEH1Z4X4-59制备了 (R)-对氯环氧苯乙烷 ((R)-pCSO)。以E. coli/pveh1Z4X4-59全细胞作为生物催化剂，在磷酸盐缓冲液体系 (Na2HPO4-NaH2PO4, 100 mmol/L, pH=7.0) 中有效拆分250 mmol/L 对氯环氧苯乙烷 (rac-pCSO) 制备 (R)-pCSO (ees > 99%)。 随后，依据6种非离子型表面活性剂对E. coli/pveh1Z4X4-59全细胞酶活力和对映选择性的影响，筛选吐温-20作为最佳添加剂，构建并优化吐温-20/缓冲液反应体系。在最优反应条件下：吐温-20的添加量为4% (体积分数)，E. coli/pveh1Z4X4-59全细胞的添加量为200 mg/mL和反应时间为12 h，初始底物浓度显著提高至800 mmol/L (123.7 g/L)，获得 (R)-pCSO的ees和产率分别为99%和45.7% (理论产率为50%)，时空产率高达4.71 g/(L·h)。反应体系放大至100 mL后，制备4.5 g (R)-pCSO 的总收率为36.3%。

Abstract:

Abstract: To efficient preparation of (R)-p-chlorostyrene oxide (pCSO), whole cells of E. coli/pveh1Z4X4-59 expressing a Phaseolus vulgaris epoxide hydrolase mutant PvEH1Z4X4-59 was used as biocatalyst to hydrolytic kinetic resolution racemic (rac-) pCSO. In the phosphate buffer (pH=7.0) system, the kinetic resolution of 250 mmol/L rac-pCSO catalyzed by E. coli/pveh1Z4X4-59 was perforemed, retaining (R)-pCSO with an over 99% enantiomeric excess (ees). Moreover, based on the effects of six nonionic surfactants on the EH activity and enantioselectivity of E. coli/pveh1Z4X4-59, Tween-20 was selected as the best reaction additive to construct a Tween-20/buffer system. In the optimized Tween-20/buffer (4%, volume fraction) system, the initial concentration of rac-pCSO catalyzed by 200 mg/mL E. coli/pveh1Z4X4-59 was significantly increased to 800 mmol/L (123.7 g/L), producing (R)-pCSO with 99% ees and 45.7% yield (theoretical yield was 50%). The space-time yield was reached 4.71 g/(L·h). Thereafter, 4.5 g (R)-pCSO was prepared with a total yield of 36.3% in extended 100 mL Tween-20/buffer reaction system.