The Stereochemistry of Hydration of Acrylyl-CoA Catalyzed by Lactyl-CoA Dehydratase

The stereochemistry of the hydration of acrylyl-CoA to D-lactyl-CoA catalyzed by lactyl-CoA dehydratase from Clostridium propionicum was established in order to further characterize the mechanism of this reaction. (E)-[3-2H1]acrylyl-CoA was converted to [3-1H,2H,3H]lactyl-CoA in [3H]H2O. Lactyl-CoA was then converted to [α-1H,2H,3H]acetate, which was predominantly of the R configuration; syn addition of H2O occurs. The maintenance of a high degree of stereochemistry is inconsistent with the radical mechanism which we proposed. An alternate mechanism is suggested.