title: Effects of magnesium salt concentrations on B-DNA overstretching transition.
abstract: In this study, we use optical tweezers to investigate the ionic effects of magnesium salt solutions on the overstretching transition of single B-DNA molecules. The experimental data are compared with those in sodium salt solutions. The overstretching transition force increases when the NaCl or MgCl(2) salt concentration increases. Magnesium cations have much stronger effects on the overstretching transition force than sodium cations. For both NaCl and MgCl(2) salt solutions, the overstretching transition force is linear with the natural logarithm of salt concentration, which confirms the theory proposed in previous paper. The modified ZZO model is applied to study the electrostatic contribution of magnesium salt solutions to the overstretching transition of single B-DNA molecules. The consistency between the experimental data and analytical results shows that the modified ZZO model can simulate the transition behavior of single B-DNA molecules in different NaCl and MgCl(2) salt solutions.
authors.affiliation: Department of Physics, National University of Singapore, 117542, Singapore, Singapore. phyfh@nus.edu.sg
authors.forename: H
authors.initials: H
authors.lastname: Fu
authors.forename: H
authors.initials: H
authors.lastname: Chen
authors.forename: C G
authors.initials: CG
authors.lastname: Koh
authors.forename: C T
authors.initials: CT
authors.lastname: Lim
mesh_terms: D004247:DNA / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D015636:Magnesium Chloride / Q000494:pharmacology*; D009690:Nucleic Acid Conformation / Q000187:drug effects*; D052898:Optical Tweezers; D012965:Sodium Chloride / Q000494:pharmacology; D055672:Static Electricity
chemical_list: D015636:Magnesium Chloride; D012965:Sodium Chloride; D004247:DNA