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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 15: Diffusion and Transport Processes

CPP 15.4: Vortrag

Dienstag, 27. März 2007, 15:15–15:30, H47

Microscopic Protein Diffusion at High Concentration — •Sebastian Busch¹, Wolfgang Doster¹, Stéphane Longeville², Victoria García Sakai^3,4, and Tobias Unruh⁵ — ¹Physics-Department E13, Technische Universität München, James Franck Straße 1, D-85747 Garching, Germany — ²Laboratoire Léon Brillouin, CEA-CNRS, DSM-DRECAM, CEA Saclay, 91191 Gif-sur-Yvette, France — ³NIST Center for Neutron Research, National Institute of Standards & Technology, Gaithersburg, MD 20899, U.S.A. — ⁴Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742, U.S.A. — ⁵Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II), TU München, Lichtenbergstr. 1, D-85747 Garching, Germany

A characteristic of the interior of cells is the high total concentration of macromolecules, occupying up to 20-30% of the total volume. This affects protein diffusion and protein association equilibria (highly nonideal solutions). The goal of our project is to understand the effect of protein-protein interactions on molecular diffusion at high concentration. The self-diffusion of myoglobin in concentrated solutions was investigated by neutron back-scattering spectroscopy. The quasi-elastic spectrum can be decomposed into two Lorentz curves: one with a linewidth increasing with Q, which is assigned to translational diffusion, the other broad Q-independent, reflecting protein-internal motions. The apparent diffusion coefficient decreases with increasing concentration and wave-vector, suggesting that protein diffusion deviates at high Q (1.75 Å^-1) from its long-time Brownian limit.