Regensburg 2007 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 6: Biopolymer Conformation and Dynamics
BP 6.3: Vortrag
Montag, 26. März 2007, 15:00–15:15, H44
Force-induced structural transitions in cross-linked DNA films — •Alexander André1,2, Theo Fischer1, Georg Maret1, and Thomas Gisler1 — 1Universität Konstanz, Konstanz, Germany — 2Université Louis Pasteur, Strasbourg, France
Single-molecule experiments have revealed that double-stranded DNA can be extended by about 60% beyond its natural contour length at nearly constant force [1,2]. The origin of this plateau in the force-extension curve is however still under debate, mainly since no direct structural information has so far been obtained from single overstretched DNA molecules. We propose an experimental approach to investigating the structure of overstretched DNA, using oriented DNA films obtained by wet-spinning. Randomly cross-linking DNA by intercalation compounds and covalent bonds between nucleobases results in elastomeric films which can be reversibly overstretched. We characterize the structure of these cross-linked films under mechanical load with X-ray diffraction and birefringence experiments.
[1] P. Cluzel, A. Lebrun, C. Heller et al., "DNA: An Extensible Molecule," Science 271, 792-794 (1996). [2] S. B. Smith, Y. Cui, A. C. Hausrath et al., "Stretching DNA beyond its B-form contour length," Biophys. J. 68, A250 (1995).