Evidence for Tyrosine at the Active Center of Bovine Carboxypeptidase B

Abstract Carboxypeptidase B is rapidly and irreversibly inhibited at pH 9.0 by 4-bromoacetamidobutylguanidine to give a product that has less than 10% activity. Amino acid analysis of the modified enzyme indicates that inactivation is caused by alkylation of 1 tyrosine residue.