title: Effect of magnesium ions on dielectric relaxation in semidilute DNA aqueous solutions.
abstract: The effect of magnesium ion Mg(2+) 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 Mg(2+) ions interact with DNA in a similar way as Na(1+) ions do, their effect being mostly describable through an enhanced screening.
authors: Institut za fiziku, 10000 Zagreb, Croatia.
authors: D
authors: D
authors: Grgičin
authors: Institut za fiziku, 10000 Zagreb, Croatia.
authors: S
authors: S
authors: Dolanski Babić
authors: Institut za fiziku, 10000 Zagreb, Croatia.
authors: T
authors: T
authors: Ivek
authors: Institut za fiziku, 10000 Zagreb, Croatia.
authors: S
authors: S
authors: Tomić
authors: Department of Physics, University of Ljubljana and J. Stefan Institute, 1000 Ljubljana, Slovenia.
authors: R
authors: R
authors: Podgornik
mesh_terms: D000042:Absorption; D000818:Animals; D004247:DNA / Q000737:chemistry*; D017097:Electric Impedance; D008274:Magnesium / Q000737:chemistry*; D012996:Solutions; D014867:Water / Q000737:chemistry*
chemical_list: D012996:Solutions; D014867:Water; D004247:DNA; D008274:Magnesium