 After NAD+ is bound to the enzyme, glycerol substrate binds to the active site in such a way as to have two coordinated interactions between two adjacent hydroxyl groups and the neighboring zinc ion.GlyDH then catalyzes the base-assisted deprotonation of the C2 hydroxyl group, forming an alkoxide.The zinc atom further serves to stabilize the negative charge on the alkoxide intermediate before the excess electron density around the charged oxygen atom shifts to form a double bond with the C2 carbon atom.