Identification and Structure Analysis of an Unusual Halohydrin Dehalogenase for Highly Chemo-, Regio- and Enantioselective Bio-Nitration of Epoxides.

We report the discovery of an unusual halohydrin dehalogenase, HHDHamb, that can work under relatively low acidic conditions and extremely low temperatures for the bio-nitration of epoxides using nitrite as a nitrating agent. The bio-nitration strategy exhibits high chemo-, regio-, and enantioselectivity, catalyzing the kinetic resolution of various epoxides to enantiopure β-nitroalcohols with nitro-bearing stereocenters in up to 41 % isolated yield and >99 % enantiomeric excess (ee). Additionally, the bio-nitration method displays a high reaction efficiency and can be performed on a gram scale. We also solved the crystal structure of HHDHamb to understand the possible structural determinants of chemoselectivity control in the bio-nitration reaction.