Slater G W, Guo H L
Department of Physics, University of Ottawa, Ontario.
Electrophoresis. 1995 Jan;16(1):11-5. doi: 10.1002/elps.1150160104.
The Ogston-Morris-Rodbard-Chrambach model (OMRCM) of gel electrophoresis assumes that the mobility mu of charged particles is proportional to the fractional volume (f) of the gel that is available to them. If the gel is random, as described by Ogston, the (semi-log) Ferguson plot is the method of choice for analyzing experimental data since it permits an estimate of the gel's mean pore size to be made. However, the Ferguson plot is rarely linear; this is usually "explained" by the deformation of the anisotropy of the particle, the nonrandom or variable architecture or the gel, or the onset of some other migration mechanism. Many authors have refined this model, but the original assumption that mu varied; is directly proportional to f has not been seriously examined. Also, the model says nothing of the effect of the field intensity, the connectivity of the gel pores, nor anything about the diffusion coefficient. We have developed a Monte-Carlo computer simulation algorithm to study the electrophoretic sieving of simple particles in gels. In this brief communication, we report important preliminary results which indicate that the basic assumptions of the OMRCM are wrong. We use a two-dimensional periodic gel since the OMRCM becomes trivial in this case. Our results show that the relationship between f and mu is not the one assumed by the OMRCM. Moreover, we find that the Einstein relation between the diffusion coefficient and the mobility is not valid. This is due to the fact that the particles do not have a uniform probability of visiting the various sites that are available to them. We thus conclude that the Ferguson plot is intrinsically nonlinear; the curvature of the plot is, in fact, related to the intensity of the electric field as well as to the degree of randomness of the gel fibers.
凝胶电泳的奥格斯顿 - 莫里斯 - 罗德巴德 - 克兰巴赫模型（OMRCM）假定带电粒子的迁移率μ与凝胶中它们可利用的分数体积（f）成正比。如果凝胶是随机的，如奥格斯顿所描述的那样，（半对数）弗格森图是分析实验数据的首选方法，因为它可以估计凝胶的平均孔径。然而，弗格森图很少是线性的；这通常被“解释”为粒子各向异性的变形、凝胶的非随机或可变结构，或者某种其他迁移机制的出现。许多作者对该模型进行了改进，但μ变化的原始假设；与f成正比这一点尚未得到认真检验。此外，该模型没有提及场强、凝胶孔隙的连通性以及扩散系数的任何影响。我们开发了一种蒙特卡罗计算机模拟算法来研究凝胶中简单粒子的电泳筛分。在这篇简短的通讯中，我们报告了重要的初步结果，这些结果表明OMRCM的基本假设是错误的。我们使用二维周期性凝胶，因为在这种情况下OMRCM变得无足轻重。我们的结果表明f和μ之间的关系并非OMRCM所假设的那样。此外，我们发现扩散系数和迁移率之间的爱因斯坦关系并不成立。这是因为粒子访问它们可利用的各个位点的概率并不均匀。因此我们得出结论，弗格森图本质上是非线性的；该图的曲率实际上与电场强度以及凝胶纤维的随机程度有关。
