Solvent effect on the conformation of the Hoechst 33258 agent Abstract: The conformational preferences of the Hoechst 33258 agent were studied with ab initio, semiempirical molecular orbital, electrostatic calculations and by Monte Carlo free energy simulations with explicit solvent representation using the adaptive umbrella sampling method. The semiempirical approach to calculating the solvation free energies was found in qualitative agreement with the Monte Carlo result. The optimal conformation in the solvent was found to be close to the previously calculated optimal conformation for binding