Transfer energetics of some nucleosides in aqueous mixtures of urea and glycerol

Abstract

Standard free energies (<img src='/image/spc_char/delta.gif' border=0><i>G</i><img src='http://www.niscair.res.in/jinfo/zerot.gif' border=0>) and entropies (<img src='/image/spc_char/delta.gif' border=0><i>S</i><img src='http://www.niscair.res.in/jinfo/zerot.gif' border=0>) of transfer of some nucleosides viz. adenosine (ado), guanosine (guo) and xanthosine (xao) from water to aqueous mixtures of urea (UH) and glycerol (GL) have been evolved from solubilities measured at different temperatures. The observed <img src='/image/spc_char/delta.gif' border=0><i>G-</i><img src='http://www.niscair.res.in/jinfo/zerot.gif' border=0> composition profiles show increasing stabilization for the nucleosides in both the cosolvent systems. The <i>T</i><img src='/image/spc_char/delta.gif' border=0>S<img src='http://www.niscair.res.in/jinfo/zerot.gif' border=0>-composition profiles are, however, complicated. So, after the elimination of various interaction effects, viz. cavity, dipole-dipole, dipole-induced dipole and dispersion interactions, the results have been discussed in the light of the hydrophilic-hydrophobic hydration effect. The solvation behaviour of the nucleosides in UH-water and GL-water mixtures help understand the relative stability of the double stranded nucleic acid helix in these. two cosolvent systems.