DNA condensation and redissolution: interaction between overcharged DNA molecules

Abstract

The effective DNA–DNA interaction force is calculated by computer simulations withexplicit tetravalent counterions and monovalent salt. For overcharged DNA molecules, theinteraction force shows a double-minimum structure. The positions and depths of theseminima are regulated by the counterion density in the bulk. Using two-dimensional latticesums and free energy perturbation theories, the coexisting phases for DNA bundles arecalculated. A DNA condensation and redissolution transition and a stable mesocrystal withan intermediate lattice constant for high counterion concentration are obtained.