Buenemann Mathias, Lenz Peter
Fachbereich Physik, Philipps-Universität Marburg, D-35032 Marburg, Germany.
Proc Natl Acad Sci U S A. 2007 Jun 12;104(24):9925-30. doi: 10.1073/pnas.0611472104. Epub 2007 Jun 1.
We studied the elastic properties and mechanical stability of viral capsids under external force-loading with computer simulations. Our approach allows the implementation of specific geometries corresponding to specific phages, such as phi29 and cowpea chlorotic mottle virus. We demonstrate how, in a combined numerical and experimental approach, the elastic parameters can be determined with high precision. The experimentally observed bimodality of elastic spring constants is shown to be of geometrical origin, namely the presence of pentavalent units in the viral shell. We define a criterion for capsid breakage that explains well the experimentally observed rupture. From our numerics we find a crossover from gamma(2/3) to gamma(1/2) for the dependence of the rupture force on the Föppl-von Kármán number, gamma. For filled capsids, high internal pressures lead to a stronger destabilization for viruses with buckled ground states versus viruses with unbuckled ground states. Finally, we show how our numerically calculated energy maps can be used to extract information about the strength of protein-protein interactions from rupture experiments.
我们通过计算机模拟研究了外力作用下病毒衣壳的弹性特性和机械稳定性。我们的方法能够实现对应特定噬菌体（如phi29和豇豆花叶病毒）的特定几何形状。我们展示了如何通过数值与实验相结合的方法高精度地确定弹性参数。实验观察到的弹性弹簧常数的双峰性被证明源于几何结构，即病毒外壳中五价单元的存在。我们定义了一个衣壳破裂的标准，该标准很好地解释了实验观察到的破裂现象。从我们的数值计算中发现，破裂力对Föppl-von Kármán数γ的依赖关系存在从γ(2/3)到γ(1/2)的转变。对于充满物质的衣壳，与具有未弯曲基态的病毒相比，高内部压力会导致具有弯曲基态的病毒更强烈的失稳。最后，我们展示了如何利用数值计算得到的能量图从破裂实验中提取有关蛋白质-蛋白质相互作用强度的信息。
