Carboxypeptidase B, also known as peptidyl-L-lysine （L-arginine） hydrolase, contains one Zn atom per molecule and can selectively hydrolyze arginine and lysine at the carboxyl end of proteins or polypeptides. CPB can be used in the production of recombinant insulin and its analogues, and the quality detection of recombinant antibodies. and also used in the production of other recombinant polypeptides.