Hevessy Z, Haramura G, Boda Z, Udvardy M, Muszbek L
Department of Clinical Chemistry, University of Debrecen, Medical School, Hungary.
Thromb Haemost. 1996 Jan;75(1):161-7.
Factor XIII (FXIII) is of high importance in the regulation of fibrinolysis. It crosslinks alpha 2-antiplasmin (alpha 2AP) and fibrin and by this way protects fibrin from the prompt elimination by plasmin. Although FXIII of platelets has been implicated in this protective mechanism, the role of platelets and platelet FXIII in the crosslinking process is far from being elucidated. As demonstrated by SDS PAGE and by immunoblotting for alpha 2AP, intact normal platelets resuspended in FXIII-free plasma or FXIII-free fibrinogen solution catalyzed the crosslinking of fibrin chains and also the crosslinking of alpha 2AP to fibrin alpha-chains. With FXIII-deficient platelets no crosslinking reaction could be observed indicating that the crosslinking with normal platelets was, indeed, due to platelet FXIII and not to another, putative platelet transglutaminase. However, the crosslinking of alpha 2AP to fibrin induced by the FXIII of intact platelets resuspended in FXIII-free plasma was considerably less extensive than the crosslinking carried out by the FXIII of normal plasma in the presence of FXIII-free platelets. Furthermore, the replacement of FXIII-free platelets by normal platelets in normal FXIII-containing plasma resulted in little, if any, difference in the crosslinking process. When crosslinking was induced by highly purified plasma FXIII the presence of intact FXIII-free platelets significantly accelerated the formation of alpha-chain polymers as well as the incorporation of alpha 2AP-fibrin alpha-chain hetero-dimer into these polymers. The results indicate that, in physiological conditions, platelet FXIII plays only a minor role in the crosslinking of alpha 2AP and fibrin; however, platelets, independently of their FXIII content, promote the crosslinking reaction by providing a catalytic surface on which the formation of highly crosslinked fibrin polymers is accelerated.
凝血因子 XIII（FXIII）在纤维蛋白溶解调节中具有高度重要性。它使α2 - 抗纤溶酶（α2AP）与纤维蛋白交联，从而保护纤维蛋白不被纤溶酶迅速清除。尽管血小板的 FXIII 参与了这一保护机制，但血小板及其 FXIII 在交联过程中的作用仍远未阐明。如 SDS - PAGE 和α2AP 的免疫印迹所示，重悬于不含 FXIII 的血浆或不含 FXIII 的纤维蛋白原溶液中的完整正常血小板催化了纤维蛋白链的交联以及α2AP 与纤维蛋白α链的交联。对于缺乏 FXIII 的血小板，未观察到交联反应，这表明与正常血小板的交联确实是由于血小板 FXIII，而非另一种假定的血小板转谷氨酰胺酶。然而，重悬于不含 FXIII 的血浆中的完整血小板的 FXIII 诱导的α2AP 与纤维蛋白的交联程度远低于正常血浆中的 FXIII 在不含 FXIII 的血小板存在下进行的交联。此外，在含正常 FXIII 的血浆中用正常血小板替代不含 FXIII 的血小板，交联过程几乎没有差异。当由高度纯化的血浆 FXIII 诱导交联时，完整的不含 FXIII 的血小板的存在显著加速了α链聚合物的形成以及α2AP - 纤维蛋白α链异二聚体掺入这些聚合物中。结果表明，在生理条件下，血小板 FXIII 在α2AP 与纤维蛋白的交联中仅起次要作用；然而，血小板无论其 FXIII 含量如何，都通过提供一个催化表面来促进交联反应，在该表面上高度交联的纤维蛋白聚合物的形成得以加速。
