title: Measurement of the torque on a single stretched and twisted DNA using magnetic tweezers.
abstract: We deduced the torque applied on a single stretched and twisted DNA by integrating the change in the molecule's extension with respect to force as it is coiled. While consistent with previous direct measurements of the torque at high forces (F>1 pN), this method, which is simple and does not require a sophisticated setup, allows for lower force estimates. We used this approach to deduce the effective torsional modulus of DNA, which decreases with force, and to estimate the buckling torque of DNA as a function of force in various salt conditions.
authors.affiliation: LPS-ENS, UMR 8550 CNRS, 24, rue Lhomond, 75231 Paris Cedex 05, France.
authors.forename: Francesco
authors.initials: F
authors.lastname: Mosconi
authors.forename: Jean François
authors.initials: JF
authors.lastname: Allemand
authors.forename: David
authors.initials: D
authors.lastname: Bensimon
authors.forename: Vincent
authors.initials: V
authors.lastname: Croquette
mesh_terms: D004247:DNA / Q000737:chemistry*; D008280:Magnetics / Q000295:instrumentation / Q000379:methods*; D009690:Nucleic Acid Conformation; D019415:Torque
chemical_list: D004247:DNA