Peak dispersion due to geometration motion in gel electrophoresis of macromolecules

A theoretical model for the motion of DNA chains through the gel under stro ng steady electric fields is proposed. It utilizes the geometration model o f the motion, which is divided into three basic phases and described by the analytical equations. The model predicts in close quantitative agreement w ith the experimental observation that the gel electrophoretic mobility of D NA, in the limit of large chains and strong fields, reaches a plateau indep endent of DNA size and electric field. The predicted value of mobility is 4 /9 of the free mobility of DNA. The calculated dispersion is proportional t o the molecular site, which is strikingly opposite to the Brownian dispersi on and also to the biased reptation dispersion but close to experimental ob servation in the pulsed field regime. The corresponding plate height due to DNA motion in the framework of obstacles is H=0.0288l, where l is DNA cont our length. Finally the model allows the simulation of electrophoretic peak profiles that show a significant asymmetry, when the migration distance is less than or equal to 100l. (C) 1999 Elsevier Science B.V. All rights rese rved.