Collet J P, Woodhead J L, Soria J, Soria C, Mirshahi M, Caen J P, Weisel J W
Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia 19104, USA.
Biophys J. 1996 Jan;70(1):500-10. doi: 10.1016/S0006-3495(96)79596-6.
Ultrastructural perturbations resulting from defects in polymerization of fibrinogen Dusart, a congenital dysfibrinogenemia with the amino acid substitution A alpha 554 arginine to cysteine, were investigated by a variety of electron microscope studies. Polymerization of this mutant fibrinogen on addition of thrombin is impaired, producing clots with decreased porosity and increased resistance to fibrinolysis, resulting in thrombotic complications in the family members with this dysfibrinogenemia. Electron microscopy of rotary-shadowed individual molecules revealed that, in contrast to control fibrinogen, most of the alpha C domains of fibrinogen or fibrin Dusart appeared to be free-swimming appendages that do not exhibit intra- or intermolecular interactions either with each other or with the central domains. The location of albumin on the alpha C domains was demonstrated by electron microscopy using anti-albumin antibodies. Electron microscopy of negatively contrasted fibrin Dusart fibers indicated that they were less ordered than control fibers and had additional mass visible. Electron microscopy of freeze-dried, unidirectionally shadowed fibers showed that they were twisted with a shorter pitch. Scanning electron microscopy revealed that intact clots were made up of thin fibers with many branch points and very small pore sizes. The viscoelastic properties of Dusart fibrin clots measured with a torsion pendulum indicated a marked increase in stiffness consistent with the structural observations.
通过多种电子显微镜研究，对由纤维蛋白原杜萨特（Dusart）聚合缺陷导致的超微结构扰动进行了研究。杜萨特是一种先天性异常纤维蛋白原血症，存在氨基酸替换，即α链554位精氨酸被半胱氨酸取代。添加凝血酶后，这种突变型纤维蛋白原的聚合受到损害，形成的凝块孔隙率降低，对纤维蛋白溶解的抵抗力增强，导致患有这种异常纤维蛋白原血症的家庭成员出现血栓并发症。对旋转阴影处理后的单个分子进行电子显微镜观察发现，与对照纤维蛋白原相比，纤维蛋白原或纤维蛋白杜萨特的大多数αC结构域似乎是自由游动的附属物，彼此之间以及与中央结构域均未表现出分子内或分子间相互作用。使用抗白蛋白抗体通过电子显微镜证实了白蛋白在αC结构域上的位置。对负染色的纤维蛋白杜萨特纤维进行电子显微镜观察表明，它们的排列不如对照纤维有序，且可见额外的物质。对冻干、单向阴影处理的纤维进行电子显微镜观察显示，它们呈扭曲状，螺距较短。扫描电子显微镜显示，完整的凝块由具有许多分支点和非常小孔隙尺寸的细纤维组成。用扭摆测量杜萨特纤维蛋白凝块的粘弹性特性表明，其刚度显著增加，这与结构观察结果一致。
