Molecular electrostatic potential [formula omitted] field. significance for DNA and its constituents.

Abstract

The studies of the electrostatic properties of molecules and in particular of biomolecules and biopolymers have, till recently, been limited essentially to the exploration of their molecular electrostatic potential (MEP). We have extended these studies to the evaluation of the molecular electrostatic field (MEF). It is shown that the different dependence upon distance of these two related properties produces substantial differences in their spatial distribution, particularly prominent in the case of macromolecules, such as the nucleic acids. Thus, while the deepest potentials are found in the grooves of DNA, the highest fields are associated with its phosphate groups. This situation has important consequences for the exploration of the biochemical reactivity of these substances, MEP being particularly appropriate for the study of the interaction with ionic, electrophilic reactants and MEF for the study of the interaction with neutral dipolar species, prominent among which is water. Abundant evidence has been provided for the significance of MEP for the interaction of the nucleic acids and their constituents with cations. Recent evidence supports the preferential hydration of phosphates in these systems, in line with the results of MEF studies.