Motivated by these initial successes, we proceeded to examine the promiscuity of HheG, HheG2 and HheG3 in the ring-opening reaction of 1-5 with other nucleophiles. To this end, we tested all combinations of 1-5 with the nucleophiles cyanide, cyanate, thiocyanate, formate, and nitrite with purified G-type HHDHs under catalyst-limiting conditions. Reactions showing the formation of ringopened product were scaled up with the best-performing HHDH in preparative whole-cell biotransformations to verify the formation of the anticipated product by NMR and HRMS. These standards were then used to assign peaks obtained by analysis of crude reaction mixtures by achiral GC to calculate TTNs of all enzymes with the tested epoxide-nucleophile combinations. In total, 15 of the 25 possible ring-opened products could be obtained (Figure ), although TTN and selectivity varied greatly between different epoxide-nucleophile combinations and different enzymes. For instance, ringopening with cyanide by HheG3 proceeded with 1-5 with synthetically useful TTNs and generally provided low to moderate enantioenrichment in the products. While the α-methylated cyanoalcohol 4b