Xiao Ye, Huang Zaixing, Wang Shengnan
State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, People's Republic of China.
J Biol Phys. 2014 Mar;40(2):179-92. doi: 10.1007/s10867-014-9344-1. Epub 2014 Apr 2.
As a coarse-gained model, a super-thin elastic rod subjected to interfacial interactions is used to investigate the condensation of DNA in a multivalent salt solution. The interfacial traction between the rod and the solution environment is determined in terms of the Young-Laplace equation. Kirchhoff's theory of elastic rod is used to analyze the equilibrium configuration of a DNA chain under the action of the interfacial traction. Two models are established to characterize the change of the interfacial traction and elastic modulus of DNA with the ionic concentration of the salt solution, respectively. The influences of the ionic concentration on the equilibrium configuration of DNA are discussed. The results show that the condensation of DNA is mainly determined by competition between the interfacial energy and elastic strain energy of the DNA itself, and the interfacial traction is one of forces that drive DNA condensation. With the change of concentration, the DNA segments will undergo a series of alteration from the original configuration to the condensed configuration, and the spiral-shape appearing in the condensed configuration of DNA is independent of the original configuration.
作为一种粗粒化模型，使用受界面相互作用的超薄弹性杆来研究多价盐溶液中DNA的凝聚。杆与溶液环境之间的界面牵引力根据杨氏-拉普拉斯方程确定。利用基尔霍夫弹性杆理论分析了DNA链在界面牵引力作用下的平衡构型。分别建立了两个模型来表征界面牵引力和DNA弹性模量随盐溶液离子浓度的变化。讨论了离子浓度对DNA平衡构型的影响。结果表明，DNA的凝聚主要由DNA自身的界面能与弹性应变能之间的竞争决定，界面牵引力是驱动DNA凝聚的力之一。随着浓度的变化，DNA片段将经历从原始构型到凝聚构型的一系列变化，并且DNA凝聚构型中出现的螺旋形状与原始构型无关。
