Interactions between short strands of DNA can be tuned from repulsive to attractive by varying solution conditions and have been quantified using small angle x-ray scattering techniques. The effective DNA interaction charge was extracted by fitting the scattering profiles with the generalized one-component method and inter-DNA Yukawa pair potentials. A significant charge is measured at low to moderate monovalent counterion concentrations, resulting in strong inter-DNA repulsion. The charge and repulsion diminish rapidly upon the addition of divalent counterions. An intriguing short range attraction is observed at surprisingly low divalent cation concentrations, ~16 mM Mg2+. Quantitative measurements of inter- DNA potentials are essential for improving models of fundamental interactions in biological systems.
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Qiu, X., Kwok, L.W., Park, H.Y., Lamb, J.S., Andresen, K., & Pollack, L. (2006). Measuring inter-DNA potentials in solution. Physical Review Letters, 96(138101). http://dx.doi.org/10.1103/PhysRevLett.96.138101
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Copyright 2006, The American Physical Society. First published as X Qiu et al, Measuring inter-DNA potentials in solution, Physical Review Letters, 96, 138101, doi: 10.1103/PhysRevLett.96.138101.