title: Critical bending torque of DNA is a materials parameter independent of local base sequence.
abstract: Short double-stranded DNA molecules exhibit a softening transition under large bending which is quantitatively described by a critical bending torque τ_{c} at which the molecule develops a kink. Through equilibrium measurements of the elastic energy of short (∼10 nm), highly stressed DNA molecules with a nick at the center we determine τ_{c} for different sequences around the nick. We find that τ_{c} is a robust materials parameter essentially independent of sequence. The measurements also show that, at least for nicked DNA, the local structure at the origin of the softening transition is not a single-stranded "bubble."
authors.affiliation: Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, CA 90095-1547, USA.
authors.forename: Juan
authors.initials: J
authors.lastname: Wang
authors.forename: Hao
authors.initials: H
authors.lastname: Qu
authors.forename: Giovanni
authors.initials: G
authors.lastname: Zocchi
mesh_terms: D001482:Base Composition; D001483:Base Sequence; D004277:DNA, Single-Stranded / Q000737:chemistry* / Q000235:genetics*; D019281:Dimerization; D004548:Elasticity; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D055672:Static Electricity; D019415:Torque
chemical_list: D004277:DNA, Single-Stranded