Immune Disease Institute, Children's Hospital Boston, Massachusetts, USA.
Biophys J. 2013 Jun 18;104(12):2671-80. doi: 10.1016/j.bpj.2013.04.052.
Fibrin fibers form the structural scaffold of blood clots. Thus, their mechanical properties are of central importance to understanding hemostasis and thrombotic disease. Recent studies have revealed that fibrin fibers are elastomeric despite their high degree of molecular ordering. These results have inspired a variety of molecular models for fibrin's elasticity, ranging from reversible protein unfolding to rubber-like elasticity. An important property that has not been explored is the timescale of elastic recoil, a parameter that is critical for fibrin's mechanical function and places a temporal constraint on molecular models of fiber elasticity. Using high-frame-rate imaging and atomic force microscopy-based nanomanipulation, we measured the recoil dynamics of individual fibrin fibers and found that the recoil was orders of magnitude faster than anticipated from models involving protein refolding. We also performed steered discrete molecular-dynamics simulations to investigate the molecular origins of the observed recoil. Our results point to the unstructured αC regions of the otherwise structured fibrin molecule as being responsible for the elastic recoil of the fibers.
纤维蛋白纤维构成了血栓的结构支架。因此，它们的机械性能对于理解止血和血栓性疾病至关重要。最近的研究表明，尽管纤维蛋白具有高度的分子有序性，但它具有弹性。这些结果激发了各种纤维蛋白弹性的分子模型，从可逆的蛋白质展开到橡胶样弹性。一个尚未被探索的重要特性是弹性回弹的时间尺度，这是纤维蛋白机械功能的关键参数，并且对纤维弹性的分子模型施加了时间约束。使用高帧率成像和基于原子力显微镜的纳米操作技术，我们测量了单个纤维蛋白纤维的回弹动力学，发现回弹速度比涉及蛋白质重折叠的模型预期的要快几个数量级。我们还进行了受控制的离散分子动力学模拟，以研究观察到的回弹的分子起源。我们的结果表明，结构纤维蛋白分子的无规αC 区域负责纤维的弹性回弹。
