Khan Md Ishak, Ferdous Sheikh Fahad, Adnan Ashfaq
Department of Mechanical and Aerospace Engineering, University of Texas at Arlington, Arlington, TX 76019, USA.
Department of Applied Engineering and Technology Management, Indiana State University, Terre Haute, IN 47809, USA.
Comput Struct Biotechnol J. 2021 Mar 26;19:1738-1749. doi: 10.1016/j.csbj.2021.03.026. eCollection 2021.
Recent nanoscopy and super-resolution microscopy studies have substantiated the structural contribution of periodic actin-spectrin lattice to the axonal cytoskeleton of neuron. However, sufficient mechanical insight is not present for spectrin and actin-spectrin network, especially in high strain rate scenario. To quantify the mechanical behavior of actin-spectrin cytoskeleton in such conditions, this study determines individual stretching characteristics of actin and spectrin at high strain rate by molecular dynamics (MD) simulation. The actin-spectrin separation criteria are also determined. It is found that both actin and spectrin have high stiffness when susceptible to high strain rate and show strong dependence on applied strain rate. The stretching stiffness of actin and forced unfolding mechanism of spectrin are in harmony with the current literature. Actin-spectrin model provides novel insight into their interaction and separation stretch. It is shown that the region vulnerable to failure is the actin-spectrin interface at lower strain rate, while it is the inter-repeat region of spectrin at higher strain rate.
近期的纳米显微镜和超分辨率显微镜研究证实了周期性肌动蛋白-血影蛋白晶格对神经元轴突细胞骨架的结构贡献。然而，对于血影蛋白和肌动蛋白-血影蛋白网络，尤其是在高应变率情况下，缺乏足够的力学见解。为了量化这种条件下肌动蛋白-血影蛋白细胞骨架的力学行为，本研究通过分子动力学（MD）模拟确定了高应变率下肌动蛋白和血影蛋白的个体拉伸特性。还确定了肌动蛋白-血影蛋白的分离标准。研究发现，肌动蛋白和血影蛋白在易受高应变率影响时都具有高刚度，并且对施加的应变率表现出强烈的依赖性。肌动蛋白的拉伸刚度和血影蛋白的强制展开机制与当前文献一致。肌动蛋白-血影蛋白模型为它们的相互作用和分离拉伸提供了新的见解。结果表明，在较低应变率下，易发生破坏的区域是肌动蛋白-血影蛋白界面，而在较高应变率下，是血影蛋白的重复间区域。
