论文标题
环DNA的扭曲动力学和屈曲不稳定：凹槽不对称和各向异性弯曲的影响
Twist dynamics and buckling instability of ring DNA: Effect of groove asymmetry and anisotropic bending
论文作者
论文摘要
通过结合分析理论和分子动力学模拟，我们研究了最初经历局部扭曲的DNA圆质粒的弛豫动力学。我们确定三个独特的时间尺度。 （i）快速放松局部弯曲，（ii）缓慢的扭曲扩散，以及（iii）屈曲过渡的时间更长。在所有这些阶段中，DNA双螺旋中的凹槽不对称产生的扭曲耦合清楚地表明。特别是，时间尺度的分离允许在阶段（II）中推断出有效的扩散方程，并具有受扭曲弯曲耦合影响的扩散系数。我们还讨论了使用重新归一化的弯曲和扭曲模量，讨论了逼真的DNA模型与最简单的各向同性扭曲蠕虫样链的映射。尽管在许多情况下有用，但它无法对屈曲过渡模式进行定量预测。
By combining analytical theory and Molecular Dynamics simulations we study the relaxation dynamics of DNA circular plasmids that initially undergo a local twist perturbation. We identify three distinctive time scales; (I) a rapid relaxation of local bending, (II) the slow twist spreading, and (III) the buckling transition taking place in a much longer time scale. In all of these stages, the twist-bend coupling arising from the groove asymmetry in DNA double helix clearly manifests. In particular, the separation of time scales allows to deduce an effective diffusion equation in stage (II), with a diffusion coefficient influenced by the twist-bend coupling. We also discuss the mapping of the realistic DNA model to the simplest isotropic twistable worm-like chain using the renormalized bending and twist moduli; although useful in many cases, it fails to make a quantitative prediction on the instability mode of buckling transition.
