Entropic elasticity of twist-storing polymers
Entropic elasticity of twist-storing polymers
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DOI：
10.1021/ma971804a
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发表时间：
1998-09-08
期刊：
影响因子：
5.5
通讯作者：
Nelson, P
中科院分区：
文献类型：
--
作者：
Moroz, JD;Nelson, P
我们研究扭转约束聚合物的统计力学。聚合物被建模为具有弯曲刚度Ak（B）T和扭转刚度Ck（B）T的波动杆。在这样的模型中，热弯曲波动通过关系Lk = Tw + Wr在几何上耦合到所施加的扭矩。我们探讨这种耦合，并找到我们的模型和最近的实验结果之间的预测一致的单双链DNA分子。该分析提供了微观扭转刚度（在螺旋重复上平均）的实验测定。使用C = 109 nm（即，扭转刚度Ck（B）T = 4.5 × 10（-19）erg cm）。该理论进一步预测，由弯曲波动引起的有效扭转刚度的热降低。最后，我们发现一个小的反射的分子手性的实验数据和解释它的DNA双链体的扭曲-拉伸耦合。
We investigate the statistical mechanics of a torsionally constrained polymer. The polymer is modeled as a fluctuating rod with bend stiffness Ak(B)T and twist stiffness Ck(B)T. In such a model, thermal bend fluctuations couple geometrically to an applied torque through the relation Lk = Tw + Wr. We explore this coupling and find agreement between the predictions of our model and recent experimental results on single lambda-DNA molecules. This analysis affords an experimental determination of the microscopic twist stiffness (averaged over a helix repeat). Quantitative agreement between theory and experiment is obtained using C = 109 nm (i.e., twist rigidity Ck(B)T = 4.5 x 10(-19) erg cm). The theory further predicts, a thermal reduction of the effective twist rigidity induced by bend fluctuations. Finally, we find a small reflection of molecular chirality in the experimental data and interpret it in terms of a twist-stretch coupling of the DNA duplex.