Detection of an anhydride intermediate in the carboxypeptidase a catalyzedhydrolysis of a peptide substrate by solid state NMR spectroscopy and its mechanistic implication

We have detected an anhydride intermediate in the CPA catalyzed proteolytic reaction of Gly-Tyr. It appears that since the zinc-bound water molecule w hich is believed to attack the scissile amide carbonyl carbon in the hydrol ysis reaction is excluded by the N-terminal amino group of Gly-Tyr, the car boxylate of Glu-270 becomes to attack the amide bond to generate the anhydr ide intermediate. (C) 1998 Elsevier Science Ltd. All rights reserved.