Alpha 2-antiplasmin (or α<sub>2</sub>-antiplasmin or plasmin inhibitor) is a serine protease inhibitor (serpin) responsible for inactivating plasmin. Plasmin is an important enzyme that participates in fibrinolysis and degradation of various other proteins. This protein is encoded by the SERPINF2 gene.

thumb|Fibrinolysis (simplified). Blue arrows denote stimulation, and red arrows inhibition.

Structure

Alpha 2-antiplasmin (α2AP) is a member of the serine protease inhibitor (serpin) superfamily and is structurally characterized by a central serpin domain flanked by unique N- and C-terminal extensions. The mature human α2AP protein consists of 452 amino acids, with a 12-residue N-terminus, a central serpin domain, and a C-terminal tail of approximately 55 residues.

Function

Alpha 2-antiplasmin serves as the primary physiological inhibitor of plasmin, the key enzyme responsible for fibrin degradation during fibrinolysis. In addition to direct inhibition, α2AP interferes with the binding of plasminogen to fibrin, further regulating the initiation of fibrinolysis. Conversely, α2AP deficiency leads to increased susceptibility to bleeding because of uncontrolled plasmin activity and rapid clot breakdown. It has been suggested, however, that the observed decreases in alpha 2-antiplasmin levels are due to a chronic state of disseminated intravascular coagulation in cirrhosis rather than defective protein synthesis.

Interactions

Alpha 2-antiplasmin has been shown to interact with:

  • Neutrophil elastase and
  • Plasmin.

See also

  • Serpin

References

Further reading

  • The MEROPS online database for peptidases and their inhibitors: I04.023