S. Ganguly et Kk. Kundu, TRANSFER ENERGETICS OF SOME DNA AND RNA BASES IN AQUEOUS MIXTURES OF UREA AND GLYCEROL, Journal of physical chemistry, 97(41), 1993, pp. 10862-10867
Standard free energies (DELTAG-degrees t) and entropies (DELTAS-degree
s t) of transfer of some DNA and RNA bases, viz., uracil (U), thymine
(T), cytosine (C), and adenine (A) from water to aqueous mixtures of u
rea (UH) and glycerol (GL) have been evaluated from solubility measure
ments at different temperatures. The observed DELTAG-degrees t and TDE
LTAS-degrees t vs composition profiles are complicated because of the
interaction effects. Elimination of the cavity effect obtained by usin
g scaled particle theory and effects due to dipole-dipole, dipole-indu
ced dipole, and dispersion interactions yielded the corresponding effe
cts as guided by the hydrophilic and hydrophobic sites of the solutes
with the components of the solvent mixtures as compared to that in wat
er. In the case of transfer entropies however, the corresponding inter
action effects are further complicated by the effect of the relative s
tructuredness of solvents. However, the overall DELTAG-degrees t behav
ior, reflecting increased stabilization of DNA-RNA bases, leads us to
conclude that both UH and GL induce denaturation of double-stranded nu
cleic acid helices.