Definition:

Carboxypeptidase N (CPN) is a plasma zinc metalloprotease that inactivates C3a, C4a, C5a, bradykinin, kalladin, and fibrinopeptides. CPN has been implicated as a major regulator of inflammation. Although deficiency of CPN produces a severe allergic syndrome, there are no reported cases of complete deficiency of CPN in humans. There are a few documented cases of partial CPN deficiency. Patients present some combination of angioedema or chronic urticaria, as well as hay fever or asthma. It has been reported that mutations in CPN1, which encodes the catalytic subunit of CPN, cause CPN deficiency.