title: The mechanism of the emergence of distinct overstretched DNA states.
abstract: Although multiple overstretched DNA states were identified in experiments, the mechanism of the emergence of distinct states is still unclear. Molecular dynamics simulation is an ideal tool to clarify the mechanism, but the force loading rates in stretching achieved by conventional all-atom DNA models are much faster, which essentially affect overstretching states. We employed a modified coarse-grained DNA model with an unprecedented low loading rate in simulations to study the overstretching transitions of end-opened double-stranded DNA. We observed two-strand peeling off for DNA with low stability and the S-DNA with high stability under tension. By introducing a melting-forbidden model which prevents base-pair breaking, we still observed the overstretching transition induced by the formation of S-DNA due to the change of dihedral angle. Hence, we confirmed that the competition between the two strain-softening manners, i.e., base-pair breaking and dihedral angle variation, results in the emergence of distinct overstretched DNA states.
authors.affiliation: State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China.
authors.forename: You-Liang
authors.initials: YL
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China.
authors.forename: Zhong-Yuan
authors.initials: ZY
authors.lastname: Lu
authors.affiliation: State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China.
authors.forename: Zhao-Yan
authors.initials: ZY
authors.lastname: Sun
mesh_terms: D004247:DNA / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D009690:Nucleic Acid Conformation; D044367:Phase Transition; D012965:Sodium Chloride; D013696:Temperature
chemical_list: D012965:Sodium Chloride; D004247:DNA