title: Excluded volume and ion-ion correlation effects on the ionic atmosphere around B-DNA: theory, simulations, and experiments.
abstract: The ionic atmosphere around a nucleic acid regulates its stability in aqueous salt solutions. One major source of complexity in biological activities involving nucleic acids arises from the strong influence of the surrounding ions and water molecules on their structural and thermodynamic properties. Here, we implement a classical density functional theory for cylindrical polyelectrolytes embedded in aqueous electrolytes containing explicit (neutral hard sphere) water molecules at experimental solvent concentrations. Our approach allows us to include ion correlations as well as solvent and ion excluded volume effects for studying the structural and thermodynamic properties of highly charged cylindrical polyelectrolytes. Several models of size and charge asymmetric mixtures of aqueous electrolytes at physiological concentrations are studied. Our results are in good agreement with Monte Carlo simulations. Our numerical calculations display significant differences in the ion density profiles for the different aqueous electrolyte models studied. However, similar results regarding the excess number of ions adsorbed to the B-DNA molecule are predicted by our theoretical approach for different aqueous electrolyte models. These findings suggest that ion counting experimental data should not be used alone to validate the performance of aqueous DNA-electrolyte models.
authors.affiliation: Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, Texas 78249-5003, USA.
authors.forename: Zaven
authors.initials: Z
authors.lastname: Ovanesyan
authors.affiliation: Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, Texas 78249-5003, USA.
authors.forename: Bharat
authors.initials: B
authors.lastname: Medasani
authors.affiliation: Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306, USA.
authors.forename: Marcia O
authors.initials: MO
authors.lastname: Fenley
authors.affiliation: Instituto de Física, Universidad Autónoma de San Luis Potosí, Álvaro Obregón 64, 78000 San Luis Potosí, San Luis Potosí, Mexico.
authors.forename: Guillermo Iván
authors.initials: GI
authors.lastname: Guerrero-García
authors.affiliation: Department of Chemistry and Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: Mónica Olvera
authors.initials: MO
authors.lastname: de la Cruz
authors.affiliation: Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, Texas 78249-5003, USA.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Marucho
mesh_terms: D003198:Computer Simulation; D059371:DNA, B-Form / Q000737:chemistry*; D004573:Electrolytes / Q000737:chemistry*; D007477:Ions / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D009010:Monte Carlo Method; D011789:Quantum Theory; D055672:Static Electricity
chemical_list: D059371:DNA, B-Form; D004573:Electrolytes; D007477:Ions