Moen Jennifer L, Gorkun Oleg V, Weisel John W, Lord Susan T
Department of Chemistry, University of North Carolina at Chapel Hill, USA.
Blood. 2003 Oct 1;102(7):2466-71. doi: 10.1182/blood-2003-01-0204. Epub 2003 Jun 12.
We synthesized BbetaArg14His fibrinogen with histidine substituted for arginine at the Bbeta thrombin-cleavage site. This substitution led to a 300-fold decrease in the rate of thrombin-catalyzed fibrinopeptide B (FpB, Bbeta 1-14) release, whereas the rate of FpA release was normal with either thrombin or the FpA-specific enzyme, batroxobin. Both thrombin- and batroxobincatalyzed polymerization of BbetaArg14His fibrinogen were significantly impaired, with a longer lag time, slower rate of lateral aggregation, and decreased final turbidity. Moreover, desA monomer polymerization was similarly impaired, demonstrating that the histidine substitution itself, and not the lack of FpB cleavage, caused the abnormal polymerization of BbetaArg14His fibrin. Scanning electron microscopy showed BbetaArg14His fibrin fibers were thinner than normal (BbetaArg14His, approximately 70 nm; normal, approximately 100 nm; P <.0001), as expected from the decreased final turbidity. We conclude that the N-terminus of the Bbeta chain is involved in the lateral aggregation of normal desAprotofibrils and that the Arg-->His substitution disrupts these interactions in BbetaArg14His fibrinogen.
我们合成了在Bβ凝血酶切割位点用组氨酸取代精氨酸的BβArg14His纤维蛋白原。这种取代导致凝血酶催化的纤维蛋白肽B（FpB，Bβ 1-14）释放速率降低300倍，而使用凝血酶或FpA特异性酶巴曲酶时，FpA的释放速率正常。BβArg14His纤维蛋白原的凝血酶和巴曲酶催化的聚合反应均受到显著损害，具有更长的延迟时间、更慢的横向聚集速率和降低的最终浊度。此外，desA单体聚合也同样受到损害，表明组氨酸取代本身而非缺乏FpB切割导致了BβArg14His纤维蛋白的异常聚合。扫描电子显微镜显示，BβArg14His纤维蛋白纤维比正常的更细（BβArg14His约为70 nm；正常约为100 nm；P <.0001），这与最终浊度降低的预期一致。我们得出结论，Bβ链的N末端参与正常desA原纤维的横向聚集，并且Arg→His取代破坏了BβArg14His纤维蛋白原中的这些相互作用。
