Fibrin is an insoluble polymer resulting from Thrombin action on Fibrinogen. The conversion is a three step process: Thrombin catalyzed release of fibrinopeptide A from Fibrinogen, non-covalent fibrin monomer association to produce protofibrils that continue to grow laterally with release of fibrinopeptide B, and covalent stabilization by FXIIIa. Mature fibrin fiber may contain approximately 100 protofibrils.
