COMPUTER-SIMULATION OF THE STRUCTURE OF DNA-MOLECULES IN AN ELECTRIC-FIELD

The structure of a model DNA chain in an electric field is investigated by Brownian dynamics simulations. The molecules have been modelled as discrete wormlike chains consisting of charged spherical subunits. The effects of hydrodynamic interactions and counterion polarization have been studied separately. Including only the polarization of the counterions causes the polyelectrolyte chain to orient in the form of a stiff rod. Taking also the hydrodynamic interactions into account, however, has the effect of deforming the chain during orientation into a bent configuration which results in a decrease of the orientational time constant. Furthermore, even without polarization effects, the hydrodynamics alone can cause an orientation of the chain, although at a lower level.