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BP: Fachverband Biologische Physik
BP 29: Posters: Biopolymers \& Biomaterials
BP 29.2: Poster
Thursday, March 17, 2011, 17:15–20:00, P3
Combining microfluidics and SAXS to access intermediate filament assembly — •Martha Brennich1, Jens Nolting1, Christian Dammann1, Bernd Nöding1, Susanne Bauch1, Harald Herrmann2, and Sarah Köster1 — 1Courant Research Centre Nano-Spectroscopy and X-Ray Imaging, University of Göttingen, Germany — 2Division of Molecular Genetics, German Cancer Research Center (DKFZ), Heidelberg, Germany
In cells, intermediate filaments (IFs) form a complex network that is part of the cytoskeleton.Vimentin is a member of the IF multi-gene family which is found in cells of mesenchymal origin like fibroblasts. We use this model system to study the first steps of the hierarchical self-assembly of protein-subunits to extended filaments in vitro upon changes in the concentration of monovalent ions. In microfluidic laminar flow mixers the ion concentration can be precisely adjusted by tuning the diffusion time scales of ions into a hydrodynamically focused protein jet. We determine the ion and protein concentration distributions by confocal microscopy and finite element method simulations. As the protein in the device flows along one spatial axis, the time axis for the assembly process is projected onto the protein flow axis and we observe different assembly states by collecting data at different positions in the device. We find that the mean square radius of gyration perpendicular to the filament axis increases as the precursor proteins aggregate laterally. This increase occurs on the same time-scale (seconds) as the diffusion of salt into the protein jet indicating a diffusion limit to the reaction rate.