Ghorbani Maryam, Mohammad-Rafiee Farshid
Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan 45195, P.O. Box 45195-1159, Iran.
Phys Rev E Stat Nonlin Soft Matter Phys. 2008 Dec;78(6 Pt 1):060901. doi: 10.1103/PhysRevE.78.060901. Epub 2008 Dec 15.
We present an elastic model for B-form DNA with variable radius to study the elastic twist-stretch coupling of stretched DNA. In this model, only two strain variables as well as the changes in the energy of the hydrogen and covalent bonds of DNA during the deformation are considered. It is found that, depending on the elastic constants, the correlation between twisting and stretching of a helical molecule can be positive or negative. It is shown that for the suitable elastic constants in the model, the twist-stretch coupling of DNA behaves nonmonotonically, and contrary to intuition, the DNA twisting and stretching are positively correlated for small distortions. This result is entirely consistent with recent experimental results.
我们提出了一种用于研究拉伸DNA弹性扭-伸耦合的可变半径B型DNA弹性模型。在该模型中，仅考虑两个应变变量以及DNA在变形过程中氢键和共价键能量的变化。研究发现，根据弹性常数的不同，螺旋分子的扭转和拉伸之间的相关性可以是正的或负的。结果表明，对于模型中合适的弹性常数，DNA的扭-伸耦合表现出非单调性，并且与直觉相反，在小变形情况下DNA的扭转和拉伸呈正相关。这一结果与最近的实验结果完全一致。
