Mazur Alexey K
UPR9080 CNRS, Université Paris Diderot, Sorbonne Paris Cité, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, Paris 75005, France.
Phys Rev E Stat Nonlin Soft Matter Phys. 2012 Jul;86(1 Pt 1):011914. doi: 10.1103/PhysRevE.86.011914. Epub 2012 Jul 16.
In recent years, significant progress in understanding the properties of supercoiled DNA has been obtained due to nanotechniques that made stretching and twisting of single molecules possible. Quantitative interpretation of such experiments requires accurate knowledge of torques inside manipulated DNA. This paper argues that it is not possible to transfer the entire magnitudes of external torques to the twisting stress of the double helix, and that a reducing torque transfer coefficient (TTC < 1) should always be assumed. This assertion agrees with simple physical intuition and is supported by the results of all-atom molecular dynamics (MD) simulations. According to MD, the TTCs around 0.8 are observed in nearly optimal conditions. Reaching higher values requires special efforts and it should be difficult in practice. The TTC can be partially responsible for the persistent discrepancies between the twisting rigidity of DNA measured by different methods.
近年来，由于纳米技术使得单分子的拉伸和扭转成为可能，在理解超螺旋DNA特性方面取得了重大进展。对此类实验进行定量解释需要准确了解被操纵DNA内部的扭矩。本文认为，不可能将外部扭矩的全部大小传递给双螺旋的扭转应力，并且应始终假定存在一个降低的扭矩传递系数（TTC < 1）。这一论断与简单的物理直觉相符，并得到了全原子分子动力学（MD）模拟结果的支持。根据MD模拟，在几乎最佳的条件下观察到TTC约为0.8。要达到更高的值需要特殊的努力，并且在实践中应该是困难的。TTC可能部分导致了通过不同方法测量的DNA扭转刚度之间持续存在的差异。
