S-N Transfer and Dual Acetylation in the S-Acetylation and N-Acetylation of 3-Phosphoglyceraldehyde Dehydrogenase by Substrates

Acetyl phosphate or p-nitrophenyl acetate acetylates a specific cysteine residue in 3-phosphoglyceraldehyde dehydrogenase to give an active acetyl-enzyme compound. By raising the pH above 7.0, the acetyl group migrates to the e-amino group of a lysine residue to form an enzymatically inactive compound. This S-N acetyl transfer is the principal route for N-acetylation of the lysine residue on the dehydrogenase. A number of considerations suggest that the cysteine and lysine residues are in close proximity although they are not near neighbors in a single peptide chain.