Modelling of DNA complexes with distamycin analogues using an ab initio continuum solvent model

Model systems related to non-covalent minor groove DNA complexes with dista mycin analogues were investigated using the Turbomole and Gaussian quantum chemical packages. The role of molecular shape, electrostatic field and con former energies in the complex formation was discussed. The ab initio calcu lations included the COSMO solvent model. If compared to vacuum computation s, polar solvent significantly destabilizes such complexes and increases co nformational flexibility of distamycin. The DNA complex formation appears t o be driven mainly by entropy lowering and complementarity of molecular sha pes. The NH moiety of the amide group preferably points to the base pair ac cording to the computations, in agreement with experimental data.