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Research Letters in Biochemistry
Volume 2008, Article ID 639829, 4 pages
Research Letter

An Antithrombin-Heparin Complex Increases the Anticoagulant Activity of Fibrin Clots

Henderson Research Centre, McMaster University, 711 Concession Street, Hamilton, L8V 1C3 Ontario, Canada

Received 15 February 2008; Accepted 5 April 2008

Academic Editor: Robert J. Linhardt

Copyright © 2008 Lesley J. Smith et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Clotting blood contains fibrin-bound thrombin, which is a major source of procoagulant activity leading to clot extension and further activation of coagulation. When bound to fibrin, thrombin is protected from inhibition by antithrombin (AT) + heparin but is neutralized when AT and heparin are covalently linked (ATH). Here, we report the surprising observation that, rather than yielding an inert complex, thrombin-ATH formation converts clots into anticoagulant surfaces that effectively catalyze inhibition of thrombin in the surrounding environment.