Advances in multi-functional biocatalyst,halohydrin dehalogenases
Optically pure epoxides and a broad range of β-substituted alcohols are valuable synthons and pharmaceutical intermediates.In recent years,the biocatalytic method provides a better way to produce these compounds because of its high chemo-,regio-and stereo-selectivity and mild,environmentally-friendly operation conditions.Halohydrin dehalogenases,occurring in the biodegradation pathways of halogenated compounds,enantioselectively catalyze the nucleophilic displacement of a halogen by a vicinal hydroxyl group in halohydrins to yield epoxides and its reverse reaction.The enzymes display a remarkable catalytic promiscuity by accepting a broad range of non-natural nucleophiles,including azide,nitrite,cyanide and even cyanate and isocyanate.Thus,it provides a useful tool for the production of enantiopure epoxides and β-substituted alcohols.This review focuses on recent developments of halohydrin dehalogenases with respect to their catalytic mechanisms and their applications in biocatalysis.At the same time,some perspectives on future research are also presented.