Alpha-1-antitrypsin-Pittsburgh. A potent inhibitor of human plasma factor XIa, kallikrein, and factor XIIf

Alpha-1-antitrypsin-Pittsburgh is a human variant that resulted from a point mutation in the plasma protease inhibitor, alpha 1-antitrypsin (358 Met----Arg). This defect in the alpha 1-antitrypsin molecule causes it to have greatly diminished anti-elastase activity but markedly increased antithrombin activity. In this report, we demonstrate that this variant protein also has greatly increased inhibitory activity towards the arginine-specific enzymes of the contact system of plasma proteolysis (Factor XIa, kallikrein, and Factor XIIf), in contrast to normal alpha 1-antitrypsin, which has modest to no inhibitory activity towards these enzymes. We determined the second-order-inactivation rate constant (k'') of purified, human Factor XIa by purified alpha 1-antitrypsin-Pittsburgh and found it to be 5.1 X 10(5) M-1 s-1 (23 degrees C), which is a 7,700-fold increase over the k'' for Factor XIa by its major inhibitor, normal purified alpha 1-antitrypsin (i.e., 6.6 X 10(1) M-1 s-1). Human plasma kallikrein, which is poorly inhibited by alpha 1-antitrypsin (k'' = 4.2 M-1 s-1), exhibited a k'' for alpha 1-antitrypsin-Pittsburgh of 8.9 X 10(4) M-1 s-1 (a 21,000-fold increase), making it a more efficient inhibitor than either of the naturally occurring major inhibitors of kallikrein (C-1-inhibitor and alpha 2-macroglobulin). Factor XIIf, which is not inhibited by normal alpha 1-antitrypsin, displayed a k'' for alpha 1-antitrypsin-Pittsburgh of 2.5 X 10(4) M-1 s-1. This enhanced inhibitory activity is similar to the effect of alpha 1-antitrypsin-Pittsburgh that has been reported for thrombin. In addition to its potential as an anticoagulant, this recently cloned protein may prove to be clinically valuable in the management of septic shock, hereditary angioedema, or other syndromes involving activation of the surface-mediated plasma proteolytic system.

Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.

Peer-reviewed research on anticoagulant and antithrombotic drug development relevant to thrombin and factor inhibition. Indexed in PubMed and verified against the NCBI record.

Узнайте, как это исследование связано с клинической практикой

More peer-reviewed studies in Разработка лекарственных препаратов.

• Novel Leech Antimicrobial Peptides — Hirunipins — Kumar et al. (2025)
• Medicinal Leech Genome Assembly — Anticoagulant Gene Catalog — Kvist et al. (2020)
• Effects of hirudotherapy on liver functions, lipid profile, and insulin sensitivity in rats with metabolic syndrome — Bilden A et al. (2026)
• HIRUDOTHERAPY IN PRESBYACUZIS PRAECOX IN CLEAN-UP WORKERS AFTER THE CHORNOBYL ACCIDENT DURING THE POST-CATASTROPHE YEARS — Zabolotnyi D, Mishchanchuk N (2019)
• [Hirudo medicinalis-leech applications in plastic and reconstructive microsurgery--a literature review] — Knobloch K et al. (2007)
• Recombinant hirudin in clinical practice: focus on lepirudin — Greinacher A, Lubenow N (2001)
• In-vitro antileishmanial potential of peptide drug hirudin — Khan H et al. (2017)
• Parenteral anticoagulants: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines — Garcia DA, Baglin TP, Weitz JI, Samama MM (2012)
• Direct thrombin inhibitors — Lee CJ, Ansell JE (2011)
• Updates on Use and Monitoring of Direct Thrombin Inhibitors — Navaei A et al. (2026)

Browse all ASH-analysed research →