When looking at the ring opening of epoxide 1 with cyanate and nitrite, the selectivity of variant M45F was again altered significantly in comparison to HheG wild type (Table ). Using cyanate as nucleophile, M45F displayed an inverted enantioselectivity, as also observed with cyanide, while activity was increased as well. In the reaction with nitrite, only HheG variant M45F exhibited considerably enhanced selectivity and activity compared to HheG wild type, while the ratio of formed nitroalcohol:diol (2c:2f) was slightly affected for all tested variants (Table ). Interestingly, HheG M45F was not only more active in epoxide ring opening reactions, but exhibited also a higher specific activity in the dehalogenation of 2-chlorocyclohexan-1-ol (2e) (0.07 U mg -1 for variant M45F compared to 0.02 U mg -1 for HheG wild type). Overall, our data using purified variants highlight that loop3947 in HheG does not only play a central role for the selectivity of HheG but also its activity. In contrast, the thermal stability of all tested variants seems to be hardly affected upon engineering of loop3947, as the determined apparent melting temperatures varied only slightly between the variants and HheG wild type (Table ).