ABSTRACT
The demand for analysis of the C-terminal sequence of proteins ever increases with new necessity to identify the base sequence corresponding to the proteins concerned. For this purpose, an enzymatic method using carboxypeptidases should be the first choice, because of a lacking of a sufficiently reliable chemical method. Carboxypeptidase is the enzyme that removes amino acids one residue at a time from the C terminus of proteins and peptides. Carboxypeptidases are classified into two groups: serine carboxypeptidase and metallo-carboxypeptidase. Metallo-carboxypeptidase usually has zinc at the active site and is inhibited by the prolonged incubation with metal chelators such as ethylenediamine tetraacetate (EDTA) and O-phenanthroline. Except small peptides, polypeptides and proteins may have secondary and/or tertiary structures during carboxypeptidase digestion, and such a structure might prevent enzymatic digestion of the C terminus so as to result in slowing down the rate of amino acid releases.
