Proton Transfers from and to the nitrogen atom (s) α (or α and β) of a doubly protected dipeptide. Gly-Gly or PG2.(or tripeptide: Gly-Gly-Gly or PG3) in anhydrous DMSO was followed by DMNR under conditions of both acid (sulphuric) and base (tetramethylguanidine) catalyzed exchange. Two kinetic processes are observed, one catalyzed by the hydrogen ion and the other by the conjugate base (P-) of the peptide (P). ...