[Conformational transitions of DNA in concentrated neutral salt solutions]

Salt anions can be arranged in lyotropic series of the action of conformational stability of DNA. This effect is universal for proteins and DNA. It is explained by the salt changes of transfer free energy of macromolecular inner groups to the solvent. Effect mechanism is the combination of anion direct interaction with the exposed inner groups and in indirect way through the changes of water structure. Individual features of the salt effect on DNA are the induced transitions in DNA duplex and the changes of differential stability of AT- and GC-base pairs. An important role in these phenomena plays the dehydration of DNA in the reduction of water activity in concentrated salt solutions. Local changes in medium polarity, hydration level of DNA molecule at different stages of their functioning can explain the regulatory role in intracellular processes, as well as selectivity and specificity of the action of individual ions in the cell.