alpha 1 -proteinase inhibitor
a member of the serpin group, a plasma protein (α1-globulin), produced primarily in the liver. It inhibits the activity of elastase, cathepsin G, trypsin, and other proteolytic enzymes. Congenital deficiency of this protein is associated with development of emphysema in young adulthood. Written also α1-antitrypsin. Called also alpha1-proteinase inhibitor.