title: Stretching short DNAs in electrolytes.
abstract: This paper is aimed at a combined theoretical and numerical study of the force-extension relation of a short DNA molecule stretched in an electrolyte. A theoretical formula based on a recent discrete wormlike chain (WLC) model of Kierfeld et al. (Eur Phys. J. E, Vol. 14, pp.17-34, 2004) and the classical OSF mean-field theory on electrostatic stiffening of a charged polymer is numerically verified by a set of Brownian dynamics simulations based on a generalized bead-rod (GBR) model incorporating long-ranged electrostatic interactions via the Debye-Hueckel potential (DH). The analysis indicates that the stretching of a short DNA can be well described as a WLC with a constant effective persistent length. This contrasts the behavior of long DNA chains that are known to exhibit variable persistent lengths depending on the ion concentration levels and force magnitudes.
authors.affiliation: Max Planck Institute for Metals Research, Heisenbergstrasse 3, D-70569 Stuttgart, Germany. jz.wang@mf.mpg.de
authors.forename: Jizeng
authors.initials: J
authors.lastname: Wang
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Fan
authors.forename: Huajian
authors.initials: H
authors.lastname: Gao
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D004247:DNA / Q000737:chemistry*; D004573:Electrolytes / Q000737:chemistry*; D008962:Models, Theoretical; D009690:Nucleic Acid Conformation; D013314:Stress, Mechanical; D013816:Thermodynamics
chemical_list: D004573:Electrolytes; D004247:DNA