Electrostatics

Positively charged or counter- ions, shown as green spheres, neutralize a large fraction of DNA’s negative charge. Electrostatic interactions are used to control DNAs conformation and interaction with other macromolecules.

We are carrying out a series of experiments designed to address fundamental questions about the interaction of positively charged or counter-ions with negatively charged nucleic acids. To maintain electrical neutrality in solution, DNA is associated with positively charged partners ranging from small ions to large proteins. Numerous biological processes are regulated by the interactions of DNA with charged molecules in vivo, e.g. gene regulation and DNA repair. In vitro, these strong interactions are exploited in the design of pharmaceuticals, small molecules that target and modify DNA. Both the biological and medical importance of DNA-charge interactions provides strong motivation for fundamental studies of the properties of these systems ranging from ionic competition to DNA condensation. We have recently applied anomalous small angle x-ray scattering (ASAXS) to probe the spatial distribution of counterions around DNA double helices in dilute solution.

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