Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
Biophys J. 2010 Nov 3;99(9):3038-47. doi: 10.1016/j.bpj.2010.08.060.
Fibrin fibers form the structural scaffold of blood clots and perform the mechanical task of stemming blood flow. Several decades of investigation of fibrin fiber networks using macroscopic techniques have revealed remarkable mechanical properties. More recently, the microscopic origins of fibrin's mechanics have been probed through direct measurements on single fibrin fibers and individual fibrinogen molecules. Using a nanomanipulation system, we investigated the mechanical properties of individual fibrin fibers. The fibers were stretched with the atomic force microscope, and stress-versus-strain data was collected for fibers formed with and without ligation by the activated transglutaminase factor XIII (FXIIIa). We observed that ligation with FXIIIa nearly doubled the stiffness of the fibers. The stress-versus-strain behavior indicates that fibrin fibers exhibit properties similar to other elastomeric biopolymers. We propose a mechanical model that fits our observed force extension data, is consistent with the results of the ligation data, and suggests that the large observed extensibility in fibrin fibers is mediated by the natively unfolded regions of the molecule. Although some models attribute fibrin's force-versus-extension behavior to unfolding of structured regions within the monomer, our analysis argues that these models are inconsistent with the measured extensibility and elastic modulus.
纤维蛋白纤维构成血栓的结构支架，并执行阻止血流的机械任务。几十年来，使用宏观技术对纤维蛋白纤维网络的研究揭示了其显著的力学性能。最近，通过对单个纤维蛋白纤维和单个纤维蛋白原分子的直接测量，探究了纤维蛋白力学的微观起源。我们使用纳米操纵系统研究了单个纤维蛋白纤维的力学性能。用原子力显微镜拉伸纤维，并收集了由激活的转谷氨酰胺酶因子 XIII（FXIIIa）交联和未交联的纤维的应力-应变数据。我们观察到 FXIIIa 的交联使纤维的刚度几乎增加了一倍。应力-应变行为表明纤维蛋白纤维表现出与其他弹性生物聚合物相似的性能。我们提出了一个机械模型，该模型拟合了我们观察到的力-延伸数据，与交联数据的结果一致，并表明纤维蛋白纤维中观察到的大延伸性是由分子的天然无规卷曲区域介导的。尽管一些模型将纤维蛋白的力-延伸行为归因于单体中结构区域的展开，但我们的分析表明，这些模型与测量的延伸性和弹性模量不一致。
