Berlin 2012 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 1: Proteins I
BP 1.8: Vortrag
Montag, 26. März 2012, 12:00–12:15, H 1058
Exploring protein self-diffusion in crowded solutions — •Felix Roosen-Runge1, Marcus Hennig1,2, Fajun Zhang1, Robert M.J. Jacobs3, Helmut Schober2, Tilo Seydel2, and Frank Schreiber1 — 1Institut für Angewandte Physik, Universität Tübingen — 2ILL, Grenoble, France — 3CRL, University of Oxford
We report a study on the self-diffusion of a globular protein, bovine serum albumin (BSA), under crowding conditions [1]. Using quasi-elastic neutron backscattering, we access the so far unexplored short-time regime of protein diffusion at nanosecond time and nanometer length scales. After separation of internal motions and rotational diffusion, the translational self-diffusion coefficients are obtained for a volume fraction range from 5% to 40%. At a biologically relevant volume fraction, the self-diffusion is slowed down by a factor of 5 compared to the dilute limit already within nanoseconds. Despite high volume fractions, no anomalous diffusion was observed at the experimental scales. Modeling the non-spherical, soft proteins with an effective hard sphere, our data agree well with predictions from colloid theory for short-time self-diffusion. This finding implies that hydrodynamic interactions are an essential part of an understanding of protein dynamics in macromolecular crowding. Comparisons are made to complementary DLS experiments [2]. The successful modeling is promising for studies on internal dynamics of proteins diffusing freely in aqueous solutions [3].
[1] F. Roosen-Runge et al., PNAS 2011, 108:11815
[2] M. Heinen et al., Soft Matter, DOI:10.1039/c1sm06242e
[3] M. Hennig et al., Soft Matter, DOI:10.1039/c1sm06609a