Berlin 2005 – wissenschaftliches Programm

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AKB: Biologische Physik

AKB 100: Poster Session I

AKB 100.17: Poster

Samstag, 5. März 2005, 16:45–18:45, Poster TU D

Helical polymer fluctuations: From rigid bodies to floppy lines — •Nils Becker and Ralf Everaers — MPI-PKS Dresden, Nöthnitzer Str. 38, 01187 Dresden

Continuous models for semiflexible polymers have been successful in explaining the elastic properties of, e.g. DNA, actin, or microtubules, as measured in many recent single-molecule experiments. Their common starting point is an interaction energy depending on the curvature of the molecule centerline. The helical symmetry of the molecule then entails a coupling between translational and rotational fluctuations.

However, the centerline is a not completely straightforward abstraction. E. g., it need not lie within the molecule material. The basic physical objects that constitute a helical molecule or filament are its monomers. They see only local interactions, which are constant along the molecule in the respective monomer body frames. It is the local energies that are important for biological interactions with filament-binding proteins and tight winding.

Both the monomer and the filament length scale are biologically relevant. To bridge their gap, we investigate possible definitions of the centerline and the corresponding elastic energy, starting from monomer-step coordinates and interactions. We also present a way for local averaging of the helix turns, and offer a description of the monomer fluctuations in terms of “screw modes”.