COMPLEMENTARY ELECTROSTATICS FOR THE STUDY OF DNA BASE-PAIR INTERACTIONS

The complementary ''lock and key'' patterns of weakly interacting mole cules are explored by mapping the topography of respective molecular e lectrostatic potentials (MESP). A new model, viz., electrostatic poten tial for intermolecular complexation (EPIC), which incorporates such M ESP features, has been employed for studying interactions between DNA base pairs, A wide variety of pairs of bases involving adenine (A), gu anine (G), and cytosine (C) are chosen as test cases. The interaction energy within the EPIC model is expressed as (1/2){Sigma V-A,V-iqB,V-i + Sigma V-B,V-iqA,V-i}, where V-A,V-i is the MESP value due to A at th e ith atom of molecule B and q(B,i) is the MESP-derived charge at this sire. The interaction energies and geometrical parameters obtained by this model agree remarkably well with the corresponding literature va lues obtained by full geometry optimization at the ab initio level. Be ing intuitively appealing and simple in application, the EPIC model se ems to have the potential of being a good predictive tool for investig ating weak intermolecular interactions.