The hydrodynamics of DNA electrophoretic stretch and relaxation in a polymer solution.
The hydrodynamics of DNA electrophoretic stretch and relaxation in a polymer solution.
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聚合物溶液中 DNA 电泳拉伸和松弛的流体动力学。
DOI：
10.1529/biophysj.104.040014
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发表时间：
2004
影响因子：
3.4
通讯作者：
H. Blanch
中科院分区：
文献类型：
--
作者：
S. Ferree;H. Blanch
DNA电泳分离理论通常将DNA视为一种自由排水的聚合物，在电场中以取决于分子有效电荷密度的速率移动。分离可以发生在从超稀聚合物溶液到紧密交联凝胶的筛分介质中。最近有研究表明，当电场和非电场同时作用于DNA分子时，DNA并不是自由排放的，就像电泳分离过程中DNA与聚合物碰撞时发生的那样。在这里，我们展示了半稀聚合物溶液屏蔽了这些力的应用所产生的水动力相互作用。荧光标记的DNA一端拴在半稀的羟乙基纤维素溶液中，在电场中比在自由溶液中拉伸得更大，并且接近自由排水行为。利用有效介质理论中发现的水动力筛分长度，由stitter建立的理论预测了无可调参数的稳定拉伸行为。去除电场后拉伸分子的弛豫数据与忽略水动力相互作用的劳斯模型预测一致。最慢弛豫时间常数tau(R)随链长变化，用数据折叠法分析时tau(R)约为L(1.9+/-0.17)，用多指数拟合分析时tau(R)约为L（2.17+/-0.17）。
Theories of DNA electrophoretic separations generally treat the DNA as a free draining polymer moving in an electric field at a rate that depends on the effective charge density of the molecule. Separations can occur in sieving media ranging from ultradilute polymer solutions to tightly cross-linked gels. It has recently been shown that DNA is not free-draining when both electric and nonelectric forces simultaneously act on the molecule, as occurs when DNA collides with a polymer during electrophoretic separations. Here we show that a semidilute polymer solution screens the hydrodynamic interaction that results from the application of these forces. Fluorescently labeled DNA tethered at one end in a semidilute solution of hydroxyl-ethyl cellulose stretch more in an electric field than they stretch in free solution, and approach free-draining behavior. The steady stretching behavior is predicted without adjustable parameters by a theory developed by Stigter using a hydrodynamic screening length found from effective medium theory. Data on the relaxation of stretched molecules after the electric field is removed agree with the Rouse model prediction, which neglects hydrodynamic interactions. The slowest relaxation time constant, tau(R), scales with chain length as tau(R) approximately L(1.9+/-0.17) when analyzed by the data collapse method, and as tau(R) approximately L(2.17+/-0.17) when analyzed by multiexponential fit.
影响因子：
14.9
作者：
Ralf M. Zimmermann;Edward C. Cox
通讯作者：
Ralf M. Zimmermann;Edward C. Cox
影响因子：
3.4
作者：
Dirk Stigter;Carlos Bustamante
通讯作者：
Dirk Stigter;Carlos Bustamante