Factor XI Activation in a Revised Model of Blood Coagulation
- 23 August 1991
- journal article
- research article
- Published by American Association for the Advancement of Science (AAAS) in Science
- Vol. 253 (5022) , 909-912
- https://doi.org/10.1126/science.1652157
Abstract
Coagulation factor XI is activated in vitro by factor XIIa in the presence of high molecular weight kininogen (HMWK) and a negatively charged surface. Factor XII deficiency is not associated with bleeding, which suggests that another mechanism for factor XI activation exists in vivo. A revised model of coagulation is proposed in which factor XI is activated by thrombin. In the absence of cofactors, thrombin is more effective (kcat/Km = 1.6 x 10(5)) than factor XIIa (1.7 x 10(4)) in activating factor XI. Dextran sulfate enhances activation of factor XI by thrombin 2000-fold; part of this effect is due to autoactivation of factor XI by activated factor XI.Keywords
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