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 while the right-handed torque needed to drive DNA to a highly overwound state
- Received 27 November 2000
DOI:https://doi.org/10.1103/PhysRevE.63.051903
©2001 American Physical Society