The spontaneous cleavage reaction of the tetrapeptide Piv-Gly Asn-Sar-
Gly-NHtBu to the C-terminal dipeptide and N-terminal succinimide dipep
tide proceeds through pre-equilibrium deprotonation of the amide group
of the asparagine side chain, Followed by intramolecular nucleophilic
attack of nitrogen on the peptide carbonyl carbon atom. General acid-
catalyzed breakdown of the intermediate then gives the products. Accor
ding to this mechanism, the reaction rate strongly increases with pH a
nd buffer concentration.