Multi-Enzyme Cascade Catalysis for the Preparation of Chiral Compound（S）-Styrene Oxide

Abstract:

In an aqueous/organic two-phase，cascade catalysis was carried out for the efficient preparation of（S）-styrene oxide（SO） by a combination of carbonyl reductase（SyS1），glucose 1-dehydrogenase（SyGDH） and halohydrin dehalogenase C（SyHheC）. The firststep was to asymmetrically reduceα-bromoacetophenone into（S）-2-bromo-1-phenylethanol（（S）-BPE） and to regenerate NADPH in situ. The optimized conditions were 100 mmol/L potassium phosphate buffer（pH 8.0）/n-hexane（v∶v=4∶6），40 mmol/L α-bromoacetophenone，80 mmol/L D-glucose，0.2 mmol/L NADP+ and 70 mg/mL wet E. coli/Sygdh-Sys1 cells（co-expressing both SyGDH and SyS1） in a volume of 1.0 mL at 35 ℃ for 8 h. The second step was dehalogenation ring-closure of（S）-BPE into（S）-SO by adding potassium phosphate buffer（pH 8.0） and 0.3 U SyHheC into the above reaction system， in a volume of 2.0 mL，at 35 ℃ for 30 min. Through two steps of enzyme catalysis，the final product（S）-SO was obtained with a molar yield of 99% and an enantiomeric excess value more than 99%.