Berlin 2005 – scientific programme

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AKB: Biologische Physik

AKB 10: Biopolymers

AKB 10.3: Talk

Friday, March 4, 2005, 10:45–11:00, TU H2013

Discontinuous unbinding transitions of filament bundles — •J. Kierfeld, T. Kühne, and R. Lipowsky — MPI für Kolloid- und Grenzflächenforschung, 14424 Potsdam

The unbinding transition of bundles of semiflexible filaments, e.g., cytoskeletal F-actin filaments, is studied theoretically. We consider bundles formed due to attractive filament interactions mediated by crosslinking sticker molecules. Using a combination of analytical arguments and Monte-Carlo simulations, it is shown that the formation of bundles of parallel filaments requires a threshold concentration of linkers which becomes independent of the filament number for large bundles. Unbinding of bundles happens in a single, discontinuous transition. We discuss the behaviour of the bundle thickness at and below the transition. In the bound phase, large bundles tend to segregate into sub-bundles due to slow kinetics. Our results are in agreement with experiments on F-actin in the presence of the crosslinking α-actinin protein.