Regensburg 2010 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
DY: Fachverband Dynamik und Statistische Physik
DY 16: Anomalous Transport I (talks contributed by BP)
DY 16.2: Vortrag
Mittwoch, 24. März 2010, 09:45–10:00, H38
Macromolecular crowding - probing the microscopic protein diffusion on nanosecond time scales — •Felix Roosen-Runge1, Marcus Hennig1,2, Fajun Zhang1, Tilo Seydel2, and Frank Schreiber1 — 1Institut für Angewandte Physik, Universität Tübingen, Germany — 2Institut Laue-Langevin, Grenoble, France
In the cellular interior, macromolecules occupy high volume fractions. This so-called macromolecular crowding affects both cellular structure and function, as reported from both simulations and kinetic measurements. From a dynamical point of view, however, protein diffusion in crowded media is far from understood. The nature of diffusion is expected to show different regimes of simple and anomalous diffusion, depending on the respective time and length scale.
Using quasi-elastic neutron scattering (QENS) at time scales of nanoseconds and length scales of several nanometers, we probe the self diffusion in crowded solutions of bovine serum albumin (BSA). The temperature dependence of the effective diffusion coefficient below thermal denaturation can be rationalised based on the Stokes Einstein relationship; addition of NaCl cause little or no changes. The concentration dependence is the most pronounced effect: the apparent diffusion coefficient, covering volume fractions ranging from 5% up to 40%, strongly decreases with increasing protein concentration. A careful deconvolution of rotational and translational contributions provides insights in the simple diffusive nature of protein motions probed by neutron backscattering. The findings are also discussed in comparison to results from colloid physics.