Role of Multivalent Cations in Condensation of DNA

We critically survey the ways in which multivalent cations may induce the condensation of DNA, and describe results using alcohol-water mixtures which shed some light on the relative roles of electrostatics and solvent structure in the condensation process. DNA condensation arises from the interplay of several forces, including stiffness, electrostatic repulsion and counterion fluctuation attraction, hydration structure, crossbridging by condensing ligands, and interhelical binding between bases whose normal intra-duplex pairing and stacking have been disrupted by interactions with solvent or ligand.