Molecular electrostatic potentials and Mulliken charge populations of DNA mini-sequences

Molecular electrostatic potentials (MEPs) are used to investigate the biochemical reactivity of DNA nucleic acid bases (NABs). As a complementary scheme, a Mulliken population analysis is performed ro determine internal charge distribution changes when nucleic acids take part in pair complexes and DNA mini-sequences. From the fact that MEPs are capable enough for predicting the formation of different hydrogen bonded pairs among NABs, it is inferred that for these compounds the electrostatic force plays a dominant role. Particular attention is paid to Watson-Crick dimers as they exhibit different preferred sites for an electrophilic attack to these of single nucleic acids. Finally, from the mini-sequences studied here, it is concluded that recognition of DNA segments proceeds at relatively short distances as a result of a poor influence of NABs on sugar and phosphate fragments. All quantum mechanical computations are performed within the density functional formulation. (C) 1998 Elsevier Science B.V.