DYNAMICS OF DNA DURING PULSED-FIELD ELECTROPHORESIS IN ENTANGLED AND DILUTE POLYMER-SOLUTIONS

Using fluorescence video microscopy, DNA electrophoretic behavior unde r field inversion conditions has been investigated in hydroxyethyl cel lulose (HEC) solutions both above and below its entanglement limit. DN A conformational fluctuation periods are found to be strongly influenc ed by the frequency of the applied electric field, DNA maximum extensi on is found to be dependent on both the frequency and the strength of the applied field. It is proposed that both above and below the HEC en tanglement limit, field inversion serves to keep the average DNA confo rmation in a size-dependent regime intermediate between full extension and random coil. In this time-averaged geometry, efficient long-chain DNA electrophoretic separation is enabled.