CARBOXYPEPTIDASE W

Carboxypeptidase Y from yeast is used for C-terminal sequencing of proteins. Also for C-terminal modification of proteins and peptides. Due to its amidase action, it is applied to the sequence analysis of peptides having amidated COOH-terminal groups such as oxytocin and vasopressin.

The glycoprotein has a molecular weight of about 61,000, has a nitrogen content of 12.74%. It is a single polypeptide chain of 442 residues with 16 residues of glucosamine in the carbohydrate moiety. Lysine is at the NH2 terminus and -Asp-Ser-Thr-Leu is the COOH-terminal sequence. The principal action of the enzyme is to remove COOH-terminal residues from polypeptide chains. It is used as a vacuolar marker enzyme for studies on protein transport and localization.