Regensburg 2010 – scientific programme

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BP: Fachverband Biologische Physik

BP 23: Biopolymers

BP 23.6: Talk

Thursday, March 25, 2010, 11:45–12:00, H43

Buckling and writhing of semiflexible polymer rings in confinement — •Katja Ostermeir, Karen Alim, and Erwin Frey — Arnold Sommerfeld Center for Theoretical Physics and CeNS, Department of Physics, Ludwig-Maximilians-Universtät München, Theresienstr. 37, D-80333 München

Cell walls or membranes impose a spatial confinement on semiflexible biopolymers such as DNA and cytoskeletal filaments. Restricting the accessible space changes a polymer’s configurations and hence its properties in biological processes. Examining semiflexible polymers rings in spherical confinement we observe substantial transformations of polymers’ shape and symmetry at relatively weak confinement.

While polymer rings with a small ratio of perimeter to persistence length would attain a planar, elliptical configuration in free space, we find that confinement forces them to buckle into banana-like shapes. We develop an analytical scaling argument which resolves a stiff polymer’s shape for small flexibilities. Our calculation agrees with shape parameter measurements from Monte Carlo simulations over ranges of confinement.

More flexible free polymers rings tend to to take on prolate configurations which are again suppressed by the confinement. We discover an increased writhing of the polymer in order to store length without sharp bending. In the semiflexible regime a bimodal distribution of writhe is found.