Editing Alpha-1 antitrypsin (section)

==Nomenclature==
The protein was initially named "antitrypsin" because of its ability to bind and irreversibly inactivate the enzyme [[trypsin]] in vitro [[covalent]]ly. Trypsin, a type of [[peptidase]], is a digestive enzyme active in the [[duodenum]] and elsewhere. In older biomedical literature it was sometimes called '''serum trypsin inhibitor''' (STI, dated terminology), because its capability as a [[trypsin inhibitor]] was a salient feature of its early study.

The term ''alpha-1'' refers to the protein's behavior on [[protein electrophoresis]]. On electrophoresis, the protein component of the blood is separated by [[electric current]]. There are several ''clusters'', the first being [[serum albumin|albumin]], the second being the ''alpha'', the third ''beta'' and the fourth ''gamma'' ([[immunoglobulin]]s). The non-albumin proteins are referred to as [[globulin]]s.

The ''alpha'' region can be further divided into two sub-regions, termed "1" and "2". Alpha-1 antitrypsin is the main [[protein]] of the [[alpha-globulin]] 1 region.

Another name used is ''alpha-1 proteinase inhibitor'' (α<sub>1</sub>-PI).