title: Structural transitions in DNA driven by external force and torque.
abstract: Experiments on single DNA molecules have shown that abrupt transitions between states of different extensions can be driven by stretching and twisting. Here we show how a simple statistical-mechanical model can be used to globally fit experimental force-extension data of Léger et al. [Phys. Rev. Lett. 83, 1066 (1999)], over a wide range of DNA molecule twisting. We obtain the mean twists, extensions, and free energies of the five DNA states found experimentally. We also predict global force-torque and force-linking number phase diagrams for DNA. At zero force, the unwinding torque for zero-force structural transition from the double helix to an unwound structure is found to be approximately -2kBT, while the right-handed torque needed to drive DNA to a highly overwound state approximately 7kBT.
authors: Department of Physics, The University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607, USA.
authors: A
authors: A
authors: Sarkar
authors: J F
authors: JF
authors: Léger
authors: D
authors: D
authors: Chatenay
authors: J F
authors: JF
authors: Marko
mesh_terms: D020029:Base Pairing; D055592:Biophysical Phenomena; D001703:Biophysics; D004247:DNA / Q000737:chemistry*; D006860:Hydrogen Bonding; D015233:Models, Statistical; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D013816:Thermodynamics; D019415:Torque
chemical_list: D004247:DNA