Nkodo A E, Garnier J M, Tinland B, Ren H, Desruisseaux C, McCormick L C, Drouin G, Slater G W
Institut Charles Sadron, Strasbourg, France.
Electrophoresis. 2001 Aug;22(12):2424-32. doi: 10.1002/1522-2683(200107)22:12<2424::AID-ELPS2424>3.0.CO;2-1.
The free-draining properties of DNA normally make it impossible to separate nucleic acids by free-flow electrophoresis. However, little is known, either theoretically or experimentally, about the diffusion coefficient of DNA molecules during free-flow electrophoresis. In fact, many authors simply assume that the Nernst-Einstein relation between the mobility and the diffusion coefficient still holds under such conditions. In this paper, we present an experimental study of the diffusion coefficient of both ssDNA and dsDNA molecules during free-flow electrophoresis. Our results unequivocally show that a simplistic use of Nernst-Einstein's relation fails, and that the electric field actually has no effect on the thermal diffusion process. Finally, we compare the dependence of the diffusion coefficient upon DNA molecular size to results obtained previously by other groups and to Zimm's theory.
DNA的自由排水特性通常使得通过自由流动电泳分离核酸成为不可能。然而，无论是在理论上还是实验上，人们对自由流动电泳过程中DNA分子的扩散系数知之甚少。事实上，许多作者只是简单地假设在这种条件下迁移率和扩散系数之间的能斯特-爱因斯坦关系仍然成立。在本文中，我们对自由流动电泳过程中ssDNA和dsDNA分子的扩散系数进行了实验研究。我们的结果明确表明，简单地使用能斯特-爱因斯坦关系是失败的，并且电场实际上对热扩散过程没有影响。最后，我们将扩散系数对DNA分子大小的依赖性与其他研究小组先前获得的结果以及齐姆理论进行了比较。
