Halohydrin dehalogenases are remarkable enzymes which possess promiscuous catalytic activity and serve as potential biocatalysts for the synthesis of chiral halohydrins, epoxides and β-substituted alcohols. The enzyme HheC exhibits a highly R enantioselectivity in the processes of dehalogenation of vicinal halohydrins and ring-opening of epoxides, which attracts more attentions in organic synthesis. Recently dozens of novel potential halohydrin dehalogenases have been identified by gene mining, however, most of the characterized enzymes showed low stereoselectivity. In this study, a novel halohydrin dehalogenase of HheA10 from Tsukamurella sp. 1534 has been heterologously expressed, purified and characterized. Substrate spectrum and kinetic resolution studies indicated the HheA10 was a highly S enantioselective enzyme toward several halohydrins, which produced the corresponding epoxides with the ee (enantiomeric excess) and E values up to >99% and >200 respectively. Our results revealed the HheA10 was a promising biocatalyst for the synthesis of enantiopure aromatic halohydrins and epoxides via enzymatic kinetic resolution of racemic halohydrins. What’s more important, the HheA10 as the first individual halohydrin dehalogenase with the highly S enantioselectivity provides a complementary enantioselectivity to the HheC.

卤代醇脱卤酶是杰出的酶，具有混杂的催化活性，并可用作合成手性卤代醇，环氧化物和β-取代醇的潜在生物催化剂。在邻卤代醇的脱卤和环氧化物的开环过程中，HheC酶表现出很高的R对映选择性，这在有机合成中引起了越来越多的关注。最近，通过基因挖掘已鉴定出数十种潜在的新型卤代醇脱卤酶，但是，大多数表征的酶显示出低的立体选择性。在这项研究中，一种新型的卤代脱卤酶HheA10从冢村sp。1534已被异源表达，纯化和鉴定。底物光谱和动力学拆分研究表明，HheA10是对几种卤代醇的高度S对映选择性酶，可产生相应的环氧化物，其ee（对映体过量）和E值分别高达> 99％和> 200。我们的结果表明，HheA10是一种通过外消旋卤代醇的酶促动力学拆分合成对映体纯的芳族卤代醇和环氧化物的有前途的生物催化剂。更重要的是，作为第一个具有高S对映选择性的单独的卤代醇脱卤酶HheA10提供了与HheC互补的对映选择性。