Levene S D, Zimm B H
Proc Natl Acad Sci U S A. 1987 Jun;84(12):4054-7. doi: 10.1073/pnas.84.12.4054.
The effect of high electric fields on the gel-electrophoretic mobility of open-circular DNA in agarose differs dramatically from that on linear molecules of the same molecular weight. At high fields, sufficiently large circular forms are prevented from migrating into the gel whereas linear molecules and smaller circular DNAs migrate normally. This effect is strongly field dependent, affecting circular molecules of decreasing size with increasing field strength. We have studied this effect with a series of plasmid DNAs ranging from 2.9 to 56 kilobase pairs using continuous and reversing-pulse electric fields. Application of reversing pulses abolishes the effect under certain conditions and supports the model for the gel electrophoresis of open-circular DNA where circular forms are trapped by engaging the free end of an agarose gel fiber.
高电场对琼脂糖中开环DNA凝胶电泳迁移率的影响与对相同分子量线性分子的影响截然不同。在高电场下，足够大的环状形式无法迁移到凝胶中，而线性分子和较小的环状DNA则正常迁移。这种效应强烈依赖于电场，随着电场强度增加，会影响尺寸逐渐减小的环状分子。我们使用连续和反向脉冲电场，对一系列大小从2.9到56千碱基对的质粒DNA研究了这种效应。在某些条件下，施加反向脉冲可消除这种效应，并支持开环DNA凝胶电泳的模型，即环状形式通过与琼脂糖凝胶纤维的自由端结合而被困住。
