Kim Young-Joo, Kim Do-Nyun
Department of Mechanical and Aerospace Engineering, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul, 08826, Republic of Korea.
Institute of Advanced Machines and Design, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul, 08826, Republic of Korea.
PLoS One. 2016 Apr 7;11(4):e0153228. doi: 10.1371/journal.pone.0153228. eCollection 2016.
In this article, we investigate the principal structural features of the DNA double helix and their effects on its elastic mechanical properties. We develop, in the pursuit of this purpose, a helical continuum model consisting of a soft helical core and two stiff ribbons wrapping around it. The proposed model can reproduce the negative twist-stretch coupling of the helix successfully as well as its global stretching, bending, and torsional rigidities measured experimentally. Our parametric study of the model using the finite element method further reveals that the stiffness of phosphate backbones is a crucial factor for the counterintuitive overwinding behavior of the duplex and its extraordinarily high torsional rigidity, the major-minor grooves augment the twist-stretch coupling, and the change of the helicity might be responsible for the transition from a negative to a positive twist-stretching coupling when a tensile force is applied to the duplex.
在本文中，我们研究了DNA双螺旋的主要结构特征及其对其弹性力学性能的影响。为此，我们开发了一个螺旋连续体模型，该模型由一个柔软的螺旋核心和围绕它的两条刚性带组成。所提出的模型能够成功再现螺旋的负扭转-拉伸耦合以及其实验测量的整体拉伸、弯曲和扭转刚度。我们使用有限元方法对该模型进行的参数研究进一步表明，磷酸骨架的刚度是双链体违反直觉的过度缠绕行为及其极高扭转刚度的关键因素， 大沟和小沟增强了扭转-拉伸耦合，并且当对双链体施加拉力时，螺旋度的变化可能是导致从负扭转-拉伸耦合转变为正扭转-拉伸耦合的原因。
