Carboxypeptidase N catalytic chain (CPN1, also known as kininase 1; MEROPS identifier M14.004) () is an extracellular glycoprotein synthesised in the liver and secreted into the blood, where it controls the activity of vasoactive peptide hormones, growth factors and cytokines by specifically removing C-terminal basic residues []. Defects in CPN1 are the cause of carboxypeptidase N deficiency (CPND). Patients affected present some combination of angioedema or chronic urticaria, as well as hay fever or astma, and have also slightly depressed serum carboxy peptidase N, suggestive of autosomal recessive inheritance of this disorder [].
