title: Extension, torque, and supercoiling in single, stretched, and twisted DNA molecules.
abstract: We reinvestigate the model originally studied by Neukirch and Marko that describes the extension, torque, and supercoiling in single, stretched, and twisted DNA molecules, which consists of a mixture of extended state and supercoiled state, using now a more accurate form of the free energy for the untwisted but stretched DNA. The original model uses an approximate form of this free energy and the agreement with experiment is only qualitative. We find that this more accurate free energy significantly improves the results, which bring them into quantitative agreement with experiment, throughout the entire force regime. This is rather surprising, considering that the theory is completely parameter-free.
authors.affiliation: Physics Department, Southern University, Baton Rouge, Louisiana 70813, USA.
authors.forename: Pui-Man
authors.initials: PM
authors.lastname: Lam
authors.affiliation: Department of Natural Sciences, Southern University, 6400 Press Drive, New Orleans, Louisiana 70126, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhen
mesh_terms: D004278:DNA, Superhelical / Q000737:chemistry*; D008954:Models, Biological; D013816:Thermodynamics; D019415:Torque
chemical_list: D004278:DNA, Superhelical