In the retaining reaction, however, the bottom side aspartate (Asp 2 ) acts as a nucleophile instead of as a base (step 2 below) , attacking the electrophilic carbon directly and forming what is refer...In the retaining reaction, however, the bottom side aspartate (Asp 2 ) acts as a nucleophile instead of as a base (step 2 below) , attacking the electrophilic carbon directly and forming what is referred to as a covalent intermediate (the enzyme is covalently attached to the terminal glucose molecule via the aspartate residue).
