Regensburg 2016 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 3: Protein Structure and Dynamics

BP 3.8: Vortrag

Montag, 7. März 2016, 12:00–12:15, H44

Protein anisotropy modulates the coupling between rotational and translational diffusion under crowding conditions — •Matthias Roos¹, Maria Ott¹, Marius Hofmann², Susanne Link¹, Jochen Balbach¹, Ernst Rössler², Alexey Krushelnitsky¹, and Kay Saalwächter¹ — ¹Martin-Luther-Universität Halle-Wittenberg, Institut für Physik, Germany — ²Universität Bayreuth, Lehrstuhl Experimentalphysik II, Germany

In vivo molecular motion of biopolymers is known to be strongly influenced by excluded-volume effects caused by the high concentration of organic matter inside cells, usually referred to as crowding conditions. In order to further understand the effects on translational and rotational diffusion, we performed pulsed-field gradient and field-cycling NMR, X-ray scattering and viscosity measurements for three proteins in water solution - αB-crystallin, bovine serum albumin and lysozyme. Our results demonstrate, on the one hand, that long-time translational diffusion quantitatively follows the expected increase of macro-viscosity upon increasing the protein concentration. The behavior of rotational diffusion, on the other hand, turns out to be protein-specific and spans the full range between the limiting cases of full coupling and full decoupling from the macro-viscosity. We show that the anisotropy of inter-protein interactions, in particular of electrostatic nature, is the main factor modulating the (de)coupling between rotational and long-time translational diffusion.