Regensburg 2007 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 6: Biopolymer Conformation and Dynamics
BP 6.2: Vortrag
Montag, 26. März 2007, 14:45–15:00, H44
DNA: From rigid base-pairs to semiflexible polymers — •Nils Becker1 and Ralf Everaers1,2 — 1Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Str. 38, 01187 Dresden — 2Laboratoire de Physique, ENS Lyon, 46, allée d’Italie, 69364 Lyon, France
The sequence–dependent elasticity of double-helical DNA on a nm length scale is captured by the rigid base–pair model, whose strains are the relative position and orientation of adjacent base–pairs. Corresponding elastic potentials have been obtained from all–atom MD simulation and from high–resolution structural data. On the scale of a hundred nm, DNA is successfully described by a continuous worm–like chain model with homogeneous elastic properties. These are characterized by a set of four elastic constants [1], recently measured on single molecules [2,3].
We present a theory that links these experiments on different scales by systematic coarse–graining. We find that the average elastic constants for random sequence DNA show reasonable agreement. However for short chains, the variability of structure and stiffness with sequence leads to large deviations from the average, including non-Gaussian bend angle distributions and elevated looping probabilities.
[1] J. F. Marko and E. D. Siggia, Biophys J 73, 2173, 1997
[2] T. Lionnet et al., Phys Rev Lett 96, 178102, 2006
[3] J. Gore et al., Nature 442, 836, 2006