Ionic strength and counterion repulsion as factors in the behavior of polyions in orienting electric fields.

The effect of counterion-counterion repulsion on the orientation of DNA, a polyion of high charge density is examined by electric-field orientation experiments. The charge species of the counterion and the ionic strength effect the orientation in a manner consistent with a theoretical treatment of the polarization of high charge density polyelectrolytes in terms of the effect of the applied field on the equilibrium distribution of condensed counterfoils on the polyion.