Critical Torque for Kink Formation in Double-Stranded DNA

• Main Authors: Hao Qu, Yong Wang, Chiao-Yu Tseng, Giovanni Zocchi
• Format: Article
• Language: English
• Published: American Physical Society 2011-11-01
• Series: Physical Review X
• Online Access: http://doi.org/10.1103/PhysRevX.1.021008

We measure the bending energy of double-stranded DNA in the nonlinear (sharply bent) regime. The measurements are obtained from the melting curves of stressed DNA ring molecules. The nonlinear elastic behavior is captured by a single parameter: the critical torque τ_{c} at which the molecule develops a kink. In this regime, the elastic energy is linear in the kink angle. This phenomenology is the same as for the previously reported case of nicked DNA. For the sequences examined, we find τ_{c}=31  pN×nm. This critical torque corresponds to a characteristic energy scale (π/2)τ_{c}=12  kT_{room} relevant for molecular biology processes associated with DNA bending.