Polymer chain statistics and conformational analysis of DNA molecules with bends or sections of different flexibility
Polymer chain statistics and conformational analysis of DNA molecules with bends or sections of different flexibility
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DOI：
10.1006/jmbi.1998.1830
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发表时间：
1998-07-03
影响因子：
5.6
通讯作者：
Bustamante, C
中科院分区：
文献类型：
--
作者：
Rivetti, C;Walker, C;Bustamante, C
蠕虫链模型经常被用来描述包括DNA在内的长的、本质上是直的聚合物分子的平均构象。本研究将蠕虫链模型的适用范围扩展到含有不同柔度的弯曲或截面的聚合物。已经明确考虑了几种情况：(I)具有单一弯曲的聚合物；(Ii)具有多个共面弯曲的聚合物；(Iii)具有两个非共面弯曲的聚合物；以及(Iv)由具有不同持续长度的部分组成的聚合物。对于每种情况，都推导出了用均方末端到末端距离来描述这种聚合物的平均构象的表达式。对于情况(I)和(Iv)，给出了端到端向量在链的初始方向上的投影表达式。本文推导的表达式已被用于研究DNA分子的序列诱导弯曲(A-Tracts)。由扫描力显微镜显示的大量含有DNA分子的A-道的均方端到端距离值导致每个A-道的平均弯曲角度为13.5度。一项类似的研究也被用来表征含有单链区域的双链DNA分子的柔韧性。对它们的均方端到端距离的分析得出单链DNA的持续长度为1.3 nm。(C)1998年学术出版社。
The worm-like chain model has often been employed to describe the average conformation of long, intrinsically straight polymer molecules, including DNA. The present study extends the applicability of the worm-like chain model to polymers containing bends or sections of different flexibility. Several cases have been explicitly considered: (i) polymers with a single bend; (ii) polymers with multiple coplanar bends; (iii) polymers with two non-coplanar bends; and (iv) polymers comprised of sections with different persistence lengths. Expressions describing the average conformation of such polymers in terms of the mean-square end-to-end distance have been derived for each case. For cases (i) and (iv), expressions for the projection of the end-to-end vector onto the initial orientation of the chain are presented. The expressions derived here have been used to investigate DNA molecules with sequence-induced bending (A-tracts). Mean-square end-to-end distance values determined from a large number of A-tract containing DNA molecules visualized by scanning force microscopy resulted in an average bend angle of 13.5 degrees per A-tract. A similar study was performed to characterize the flexibility of double-stranded DNA molecules containing a single-stranded region. Analysis of their mean-square end-to-end distance yielded a persistence length of 1.3 nm for single-stranded DNA. (C) 1998 Academic Press.