sentences:  This means that the proton which the α-carbon grabs is from the water that just attacked the β-carbon.What this implies is that the hydroxyl group and the proton from water are both added from the same side of the double bond, a syn addition.This allows ECH to make an S stereoisomer from 2-trans-enoyl-CoA and an R stereoisomer from the 2-cis-enoyl-CoA.