R-2-Bromobutyric acid is a very important intermediate for the synthesis of agrochemicals and pharmaceuticals. Bioresolution of rac-2-bromobutyric acid (rac-2-BBA) provides a promising process for R-2-bromobutyric acid (R-2-BBA) production. The fluoroacetate dehalogenase (FAcD) has been always studied in the defluorination process. We found that FAcD RPA1163 showed detectable activity but no enantioselectivity towards rac-2-BBA. The iterative saturation mutagenesis (ISM) of FAcD RPA1163 resulted in a mutant H155V/W156R/Y219M, which catalyzed the kinetic resolution of rac-2-BBA to produce R-2-BBA with enhanced activity and enantioselectivity (99.3% ee). The high preference for S-2-bromobutyric acid (S-2-BBA) is of synthetic value. Molecular docking analysis indicated that the H155V/W156R/Y219M mutation reduced steric hindrance and broadened the halide pocket. It is not only the steric hindrance but also the electrostatic environment that has an effect on the activity and enantioselectivity.

R -2-溴丁酸是农用化学品和药物合成中非常重要的中间体。rac-2-溴丁酸（rac-2-BBA）的生物拆分为R -2-溴丁酸（R -2-BBA）的生产提供了一个有希望的过程。氟乙酸脱卤酶（FAcD）一直在脱氟过程中得到研究。我们发现FAcD RPA1163表现出可检测到的活性，但对rac-2-BBA没有对映选择性。FAcD RPA1163的迭代饱和诱变（ISM）产生了一个突变体H155V / W156R / Y219M，该突变体催化rac-2-BBA的动力学拆分，从而产生具有增强的活性和对映选择性（99.3％ee）的R -2-BBA 。对S的高度偏爱-2-溴丁酸（S -2-BBA）具有合成价值。分子对接分析表明，H155V / W156R / Y219M突变可减少空间位阻，并扩大卤化物口袋。影响空间活性和对映选择性的不仅是位阻，而且还包括静电环境。