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arXiv · 1307.0715

Effect of magnesium ions on dielectric relaxation in semidilute DNA aqueous solutions

Danijel Grgičin·Sanja Dolanski Babić·Tomislav Ivek·Silvia Tomić·Rudi Podgornik
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Abstract

The effect of magnesium ion Mg2+ on the dielectric relaxation of semidilute DNA aqueous solutions has been studied by means of dielectric spectroscopy in the 100 Hz-100 MHz frequency range. De Gennes-Pfeuty-Dobrynin semidilute solution correlation length is the pertinent fundamental length scale for sufficiently low concentration of added salt, describing the collective properties of Mg-DNA solutions. No relaxation fingerprint of the DNA denaturation bubbles, leading to exposed hydrophobic core scaling, was detected at low DNA concentrations, thus indicating an increased stability of the double-stranded conformation in Mg-DNA solutions as compared to the case of Na-DNA solutions. Some changes are detected in the behavior of the fundamental length scale pertaining to the single molecule DNA properties, reflecting modified electrostatic screening effects of the Odijk-Skolnick-Fixman type. All results consistently demonstrate that Mg2+ ions interact with DNA in a similar way as Na1+ ions do, their effect being mostly describable through an enhanced screening.

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Danijel Grgičin, Sanja Dolanski Babić, Tomislav Ivek, Silvia Tomić, Rudi Podgornik. 2013-11-19. Effect of magnesium ions on dielectric relaxation in semidilute DNA aqueous solutions. https://doi.org/10.1103/physreve.88.052703

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