Strzelecki, Janusz; Peplowski, Lukasz; Lenartowski, Robert; Nowak, Wieslaw; Balter, Aleksander
Mechanical transition in a highly stretched and torsionally constrained DNA
PHYSICAL REVIEW E, 89 Art. No. 020701, FEB 27 2014

We show results of our high force (up to 1.8 nN) atomic force microscopy force spectroscopy measurements of a double stranded DNA. We have found that the force spectra of torsionally constrained molecules display a small plateau occurring at a force of approximately 1 nN. This transition is absent in molecules with rotational freedom. Based on all-atom molecular dynamics simulations, we suggest that this plateau is a result of reducing the diameter of a double helix through extreme stretching. The simulation suggests that the molecule is forced into a form resembling an underwound P-DNA, with bases protruding outside of the backbones. These results broaden our understanding of the fundamental aspects of DNA nanomechanics.

DOI:10.1103/PhysRevE.89.020701

Find full text with Google Scholar.