title: Elasticity theory of the B-DNA to S-DNA transition.
abstract: We propose in this note a simple model--the two-state Worm Like Chain--to describe the elasticity of the recently discovered stress-induced transformation from B-DNA to S-DNA. The model reduces for low tractions to the well-known Worm Like chain theory, which is used to describe the elastic properties of B-DNA, while in the limit of high chain-bending moduli it reduces to the two-state Ising model proposed by Cluzel et al. for the B-S transition [Cluzel, P., A. Lebrun, C. Heller, R. Lavery, J-L. Viovy, D. Chatenay, and F. Caron. 1996. DNA: an extensible molecule. Science. 271:792-794]. Our model can be treated analytically to produce an explicit form of the force-extension relationship which agrees reasonably with the observations. We use the model to show that conformational fluctuations of the chain play a role also for the B to S transformation.
authors.affiliation: Department of Physics, University of California at Los Angeles, 90024, USA.
authors.forename: A
authors.initials: A
authors.lastname: Ahsan
authors.forename: J
authors.initials: J
authors.lastname: Rudnick
authors.forename: R
authors.initials: R
authors.lastname: Bruinsma
mesh_terms: D004247:DNA / Q000737:chemistry*; D004548:Elasticity; D008956:Models, Chemical; D009690:Nucleic Acid Conformation; D013314:Stress, Mechanical
chemical_list: D004247:DNA