<unk>  is a 52-kDa serpin and, in medicine, it is considered the most prominent serpin; the terms α1-antitrypsin and protease inhibitor (Pi) are often used interchangeably. Most serpins inactivate enzymes by binding to them covalently. These enzymes are released locally in relatively low concentrations where they are immediately cleared by proteins such as<unk> . In the acute phase reaction, a further elevation is required to "limit" the damage caused by activated neutrophil granulocytes and their enzyme elastase, which breaks down the connective tissue fiber elastin. Besides limiting elastase activity to limit tissue degradation, A1PI also acts to induce locomotion of lymphocytes through tissue including immature T cells through the thymus where immature T cells mature to become immunocompetent T cells that are released into tissue to elevate immune responsiveness. Like all serine protease inhibitors,<unk>  has a characteristic secondary structure of beta sheets and<unk>  helices. Mutations in these areas can lead to non-functional proteins that can polymerise and accumulate in the liver (infantile hepatic cirrhosis).
Alpha-1 antitrypsin
Haptocorrin
Gamma globulin
Hepcidin
Ovoferrin
Thyroglobulin
Beta defensin
Defensin