Theory for the extension of a linear polyelectrolyte attached at one end in an electric field
Theory for the extension of a linear polyelectrolyte attached at one end in an electric field
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一端附着的线性聚电解质在电场中的延伸理论
DOI：
10.1002/bip.360290806
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发表时间：
1990
期刊：
影响因子：
2.9
通讯作者：
Steven B. Smith
中科院分区：
文献类型：
--
作者：
J. Michael Schurr;Steven B. Smith
本文提出了一种简单的理论，用于研究一端附着在电场中的均匀带电线性多极化的扩展。对于由大量(N)库恩长度(b)组成的多角体，电场方向(E)的平均扩展精确地由Rz = (b/ a) in （sinh (NA)/NA）给出，其中a = EQb/kBT， Q是与每个库恩长度相关的有效电荷。对于E的任何值，无论多小，一个足够长的多边形，使得NA < 1.0，本质上是完全展开的。当A≪1.0时，就像DNA在弱电场中的情况一样，即使链条的杆和尾可能完全对齐，链条的头端也只是弱定向。在线性条件下，NA < 1.0， Rz与E、Q、N2成正比。对处于线性状态的链，计算了链元的线性密度。这一理论为通过直接显微测量荧光标记的环状dna的Rz与E来确定产物Qb提供了基础，这些dna在拓扑结构上靠近凝胶的空隙或表面。下面的文章描述了这一建议的实验实现。
A simple theory is developed for the extension of a uniformly charged linear polyion attached at one end in an electric field. For a polyion consisting of a very large number (N) of Kuhn lengths (b), the mean extension in the direction of the electric field (E) is given accurately by Rz = (b/A) In (sinh (NA)/NA), where A = EQb/kBT and Q is the effective charge associated with each Kuhn length. For any value of E, no matter how small, a polyion of sufficient length, such that NA ≫ 1.0, will be essentially fully extended. When A ≪ 1.0, as is the case for DNA in weak electric fields, the head end of the chain is only weakly oriented, even though the stem and tail may be completely aligned. In the linear regime, NA < 1.0, Rz is proportional to E, Q, and N2. The linear density of chain elements is calculated for a chain in the linear regime. This theory provides a basis to determine the product Qb from direct microscopic measurements of Rz vs. E for fluorescent‐labeled circular DNAs that are topologically snared near voids or surfaces of gels. Experimental realization of this suggestion is described in the following paper.