Dresden 2011 – scientific programme

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BP: Fachverband Biologische Physik

BP 21: Biopolymers and Biomaterials II (with CPP)

BP 21.3: Talk

Wednesday, March 16, 2011, 11:00–11:15, ZEU 260

Mechanics and Dynamics of Individual Intermediate Filaments — •Bernd Nöding, Susanne Bauch, and Sarah Köster — Courant Research Centre Nano-Spectroscopy and X-Ray Imaging, University of Göttingen, Germany

The mechanical rigidity of a polymer is characterized by its persistence length L_P. In the case of the intermediate filament (IF) protein vimentin, L_P was found to be on the order of one micrometer using static measurement methods. In contrast, we perform dynamic measurements on fluorescently labeled IFs confined in microchannels, thereby realizing the Odijk confinement regime. Since IFs can be classified as semiflexible polymers (L ≈ L_P) we assume the worm-like chain model for our fluctuation analysis. The channel walls are included as a parabolic potential in our calculations. Interaction of the filament and the confining microchannel gives rise to an additional length scale, the deflection length λ. We combine IF data with literature data for actin. Thereby we can access both the channel dimension d and L_P, which define the scaling law connecting λ and L_P, λ = a · d^2/3 · L_P^1/3. The scaling law is fully confirmed by our experiments. Additionally our dynamic measurements yield L_P on the order of one micrometer for vimentin filaments.