Carboxypeptidase N (CPN),  also known as an arginine/lysine carboxypeptidase, kininase
I, or anaphyla-toxin inactivator, is a member of a larger family of zinc metallopeptidases (16).
1/2]) of a few seconds in plasma by host proteases such as kininase
and angiotensin converting enzyme (ACE) in vivo.
The concern arises when patients are taking an ACE inhibitor, which is a kininase
II blocker and will inhibit the catabolism of bradykinin.
In another study, Carmignani et al (72) showed a significant increase in plasma angiotensin converting enzyme (ACE), kininase
I and kallikrein activities in the rats exposed to lead for 10 months beginning at early age.
Angiotensin II is formed from angiotensin in a reaction catalyzed by angiotensin-converting enzyme (ACE, kininase
3; also known as lysine carboxypeptidase, kininase
I, anaphylatoxin inactivator, or plasma carboxypeptidase B) and the more recently identified carboxypeptidase U (CPU; EC 3.
Bioregulation of kinins: kallikreins, kininogens, and kininases