Theory for the hydrodynamic and electrophoretic stretch of tethered B-DNA.
Theory for the hydrodynamic and electrophoretic stretch of tethered B-DNA.
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DOI：
10.1016/s0006-3495(98)74039-1
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发表时间：
1998-09
影响因子：
3.4
通讯作者：
Dirk Stigter;Carlos Bustamante
中科院分区：
文献类型：
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作者：
Dirk Stigter;Carlos Bustamante
我们发展了在均匀流体动力流动或均匀外加电场中固定在某一点上的B-DNA的拉伸和受力的理论。被束缚在电场中的链被认为受到自由电泳的影响，而自由沉淀则相反方向补偿。这允许使用自由电泳法的结果来包括小离子的影响。链上的力是由一系列椭球线段推导出来的，每个椭球线段的持续长度是蠕虫链的两倍。这些节段之间的水动力相互作用是基于绕长椭球的流动的长程极限，如从等效的斯托克斯球得到的。用Marko和Siggia(1995)的熵弹性关系导出了链的伸长。28：8759-8770)，用于恒张力下的聚合物链的每个链段。我们通过与基于玻尔兹曼平均取向的直段、自由连接段的延伸结果的比较来证明这种方法是正确的。预测结果与Perkins等人1995年的延伸流实验很好地吻合。258：83-87，以及Smith和Bendich的电泳拉伸实验(1990生物聚合物。29：1167-1173)。我们发现，Long等人提出的流体力学拉伸和电泳拉伸的等价性。(1996 Phys.莱特牧师。76：3858-3861；1996生物聚合物39：755-759)，仅对非常小的链变形有效，但一般不有效。
We have developed a theory for the extension and force of B-DNA tethered at a fixed point in a uniform hydrodynamic flow or in a uniform applied electric field. The chain tethered in an electric field is considered to be subject to free electrophoresis compensated by free sedimentation in the opposite direction. This allows the use of results of free electrophoresis for including the effects of small ions. The force on the chain is derived for a sequence of ellipsoidal segments, each twice the persistence length of the wormlike chain. Hydrodynamic interaction between these segments is based on the long-range limit of flow around the prolate ellipsoids, as derived from equivalent Stokes spheres. The chain extension is derived by applying the entropic elasticity relation of Marko and Siggia (1995Macromolecules. 28:8759–8770) to each segment for polymer chains under constant tension. We justify this procedure by comparing with extension results based on the Boltzmann averaged orientation of straight, freely jointed segments. Predicted results agree well with recent extension-flow experiments by Perkins et al., 1995.Science. 258:83–87, and with electrophoretic stretch experiments by Smith and Bendich (1990Biopolymers. 29:1167–1173) on fluorescently stained B-DNA. We find that the equivalence of hydrodynamic and electrophoretic stretch, proposed by Long et al. (1996 Phys. Rev. Lett. 76:3858–3861; 1996 Biopolymers 39:755–759), is valid only for very small chain deformations, but not in general.