title: Reentrant behavior of divalent-counterion-mediated DNA-DNA electrostatic interaction.
abstract: The problem of DNA-DNA interaction mediated by divalent counterions is studied using computer simulation. Although divalent counterions cannot condense free DNA molecules in solution, we show that if DNA configurational entropy is restricted, divalent counterions can cause DNA reentrant condensation similar to that caused by tri- or tetravalent counterions. DNA-DNA interaction is strongly repulsive at small or large counterion concentration and is negligible or slightly attractive for a concentration in between. Implications of our results to experiments of DNA ejection from bacteriophages are discussed. The quantitative result serves to understand electrostatic effects in other experiments involving DNA and divalent counterions.
authors.affiliation: School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, Georgia 30332-0430, USA.
authors.forename: Seil
authors.initials: S
authors.lastname: Lee
authors.forename: Tung T
authors.initials: TT
authors.lastname: Le
authors.forename: Toan T
authors.initials: TT
authors.lastname: Nguyen
mesh_terms: D004247:DNA / Q000737:chemistry*; D007477:Ions; D008958:Models, Molecular; D009997:Osmotic Pressure; D055672:Static Electricity
chemical_list: D007477:Ions; D004247:DNA