Klenin K V, Vologodskii A V, Anshelevich V V, Dykhne A M, Frank-Kamenetskii M D
Institute of Molecular Genetics, USSR Academy of Sciences, Moscow.
J Mol Biol. 1991 Feb 5;217(3):413-9. doi: 10.1016/0022-2836(91)90745-r.
We treat supercoiled DNA within a wormlike model with excluded volume. A modified Monte Carlo approach has been used, which allowed computer statistical-mechanical simulations of moderately and highly supercoiled DNA molecules. Even highly supercoiled molecules do not have a regular shape, though with an increase in writhing the chains look more and more like branched interwound helixes. The averaged writhing (Wr) approximately 0.7 delta Lk. The superhelical free energy F is calculated as a function of the linking number. Lk. The calculations have shown that the generally accepted quadratic dependence of F on Lk is valid for a variety of conditions, though it is by no means universal. Significant deviations from the quadratic dependence are expected at high superhelical density under ionic conditions where the effective diameter of DNA is small. The results are compared with the available experimental data.
我们在具有排除体积的蠕虫状模型中处理超螺旋DNA。采用了一种改进的蒙特卡罗方法，该方法允许对中度和高度超螺旋DNA分子进行计算机统计力学模拟。即使是高度超螺旋分子也没有规则的形状，尽管随着扭曲的增加，链看起来越来越像分支相互缠绕的螺旋。平均扭曲（Wr）约为0.7ΔLk。超螺旋自由能F作为连接数Lk的函数进行计算。计算表明，F对Lk的普遍接受的二次依赖性在各种条件下都是有效的，尽管它绝不是普遍适用的。在DNA有效直径较小的离子条件下，在高超螺旋密度下预计会有与二次依赖性的显著偏差。将结果与现有的实验数据进行了比较。
