The resulting data do not only confirm the improvements in enantioselectivity observed during screening, but also highlight a concomitant increase in activity upon mutagenesis, which is especially evident for HheG M45F. This variant did not only achieve higher conversions compared to wild type in all studied epoxide ring opening reactions (Table ), but displayed also an almost 10-fold higher specific activity in the azidolysis of 1 (Table ), as determined by our recently published BTB assay. Moreover, variant M45F was more than twice as active as HheG wild type in the ring opening of 3 with azide, while variant T44F exhibited the highest specific activity (Table ) and the highest enantioselectivity (E=44, Table ) in this reaction.