WHAT CONTROLS PARTITIONING OF THE NUCLEIC-ACID BASES BETWEEN CHLOROFORM AND WATER

The free energies of solvation for six nucleic acid bases in water and chloroform are predicted using the SM5.4/A quantum mechanical self-co nsistent-field solvation model. We obtain a mean unsigned deviation fr om experiment of 0.2 log(10) units in the partition coefficients, lend ing extra credibility to the predicted solvation free energies. Predic tions are then made for an additional six unnatural nucleic acid bases for which no experimental data are available. Functional group contri butions to the solvent-solvent partitioning phenomenon are examined, a nd the validity of fragment-based partitioning models is assessed.