Alpha-1 antitrypsin is a serine protEAse inhibitor and member of the serpin superfamily.1 It has a five-stranded A -sheet and a mobile rEActive center loop that acts as a pseudosubstrate for various protEAses. Alpha-1 antitrypsin binds to a protEAse, undergoes proteolytic clEAvage, and forms a covalent linkage between a carboxyl group in the rEActive loop and the serine hydroxyl of the protEAse active site, effectively inactivating the enzyme which is then clEAred from circulation. The primary targets of alpha-1 antitrypsin are neutrophil elastase and proteinase 3, however, it also inhibits trypsin, kallikreins 7 and 14, and matriptase.2 Alpha-1 antitrypsin protects the lower respiratory tract from proteolytic destruction via inhibition of neutrophil elastase and reduced serum levels of alpha-1 antitrypsin have been linked to EArly-onset liver disEAse and emphysema.3 Alpha-1 antitrypsin is an acute-phase protein that reduces production of inflammatory cytokines, inhibits apoptosis, blocks leukocyte degranulation and migration, as well as suppresses NF-B nuclEAr translocation in monocytes. It delays disEAse onset in mouse models of inflammatory disEAse, including collagen-induced arthritis and experimental autoimmune encephalomyelitis (EAE). Technical Information Synonyms A1A A1AT AAT 1-Antitrypsin Purity 90% estimated by SDS-PAGE Source Human plasma MW 54,000 kDa UniProt Accession P01009