Elastic response of single DNA molecules exhibits a reentrant collapsing transition.

@article{Murayama2003ElasticRO,
  title={Elastic response of single DNA molecules exhibits a reentrant collapsing transition.},
  author={Yoshihiro Murayama and Yoshihiko Sakamaki and Masaki Sano},
  journal={Physical review letters},
  year={2003},
  volume={90 1},
  pages={018102}
}
We measured the elastic response of single DNA molecules at various concentrations of the trivalent cation, spermidine. When added spermidine caused the DNA to collapse, the force-extension curves showed either plateaus or stick-release patterns depending on the concentration. The periodic stick-release response determines a characteristic length, which may reflect toroidal supercoiling. At high concentrations of spermidine, we observed the reelongation of single molecules of collapsed DNA… CONTINUE READING