Entropy-volume correlation with hydration changes in DNA-ligand interactions

We report an apparent linear correlation between the entropy and the volume change for the association of the minor groove ligand, distamycin A, to synthetic polynucleotides of known sequence. The slope of the fitted line, ΔS o /ΔV o , is significantly more shallow than that reported for the protonation of small organic acids and reflects, therefore, a smaller compression of the water dipoles arrayed as spine in the minor groove of the double helix prior to the release into the solvent during the binding process