Wang Jizeng, Fan Xiaojun, Gao Huajian
Max Planck Institute for Metals Research, Heisenbergstrasse 3, D-70569 Stuttgart, Germany.
Mol Cell Biomech. 2006 Mar;3(1):13-9.
This paper is aimed at a combined theoretical and numerical study of the force-extension relation of a short DNA molecule stretched in an electrolyte. A theoretical formula based on a recent discrete wormlike chain (WLC) model of Kierfeld et al. (Eur Phys. J. E, Vol. 14, pp.17-34, 2004) and the classical OSF mean-field theory on electrostatic stiffening of a charged polymer is numerically verified by a set of Brownian dynamics simulations based on a generalized bead-rod (GBR) model incorporating long-ranged electrostatic interactions via the Debye-Hueckel potential (DH). The analysis indicates that the stretching of a short DNA can be well described as a WLC with a constant effective persistent length. This contrasts the behavior of long DNA chains that are known to exhibit variable persistent lengths depending on the ion concentration levels and force magnitudes.
本文旨在对在电解质中拉伸的短DNA分子的力-伸长关系进行理论与数值相结合的研究。基于Kierfeld等人（《欧洲物理杂志E》，第14卷，第17 - 34页，2004年）最近的离散蠕虫状链（WLC）模型以及关于带电聚合物静电硬化的经典OSF平均场理论的一个理论公式，通过一组基于广义珠-杆（GBR）模型的布朗动力学模拟进行了数值验证，该模型通过德拜-休克尔势（DH）纳入了长程静电相互作用。分析表明，短DNA的拉伸可以很好地描述为具有恒定有效持久长度的WLC。这与长DNA链的行为形成对比，已知长DNA链根据离子浓度水平和力的大小表现出可变的持久长度。
