Journal of Thrombosis and Haemostasis
Original Item ID
Plasma alpha2-antiplasmin (α2AP) is a rapid and effective inhibitor of the fibrinolytic enzyme plasmin. Congenital α2AP deficiency results in a severe hemorrhagic disorder due to accelerated fibrinolysis. It is well established that in the presence of thrombin-activated factor XIII (FXIIIa), α2AP becomes covalently ligated to the distal α chains of fibrin or fibrinogen at lysine 303 (two potential sites per molecule). Some time ago we showed that α2AP is covalently linked to plasma fibrinogen . That singular observation led to our hypothesis that native plasma factor XIII (FXIII), which is known to catalyze covalent cross-linking of fibrinogen in the presence of calcium ions, can also incorporate α2AP into fibrinogen in the circulation.
Results and Conclusions:
We now provide evidence that FXIII incorporates I125-labelled α2AP into the Aα-chain sites on fibrinogen or fibrin. We also measured the content of α2AP in isolated plasma fibrinogen fractions by ELISA and found that substantial amounts were present (1.2–1.8 moles per mole fibrinogen). We propose that α2AP becomes ligated to fibrinogen while in the circulation through the action of FXIII, and that its immediate presence in plasma fibrinogen contributes to regulation of in vivo fibrinolysis.
Mosesson, Michael W.; Siebenlist, Kevin R.; Hernandez, Irene; Lee, K. N.; Christiansen, V. J.; and McKee, P. A., "Evidence that α2-Antiplasmin Becomes Covalently Ligated to Plasma Fibrinogen in the Circulation: a New Role for Plasma Factor XIII in Fibrinolysis Regulation" (2008). Biomedical Sciences Faculty Research and Publications. 217.
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