Anomalous migration of DNA

A quantitative model for the electrophoretic mobility of very small fragments of A-DNA and Z-DNA in gel is described. The model is a synthesis of counterion condensation features of ionic oligomers, screening of the hydrodynamic interactions of an oligomer, and a suitable extension of the Ogstron pore-size distribution model of gel migration. Anomalous migration of very small fragments of A- and Z-DNA is predicted. The electrophoretic mobility is an increasing function of its length for small fragments, reaches a maximum and then starts to slow down for larger fragments. For very small sequence lengths studied here, A-DNA migrates faster than Z-DNA of the same length in polyacrylamide gel.