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Dec 8 – 10, 2020 Online only
Online event
Europe/Berlin timezone

Short-Time Self-Diffusion of Salt- and Temperature-Dependent Protein Clusters

Dec 9, 2020, 2:30 PM
3h 30m
Online event

Online event

Speaker

Tilo Seydel (Institut Max von Laue - Paul Langevin)

Description

Salt-induced charges in aqueous suspensions of proteins can give rise to complex phase diagrams including homogeneous solutions, large aggregates, and reentrant dissolution regimes. Moreover, depending on the temperature, a liquid-liquid phase separation may occur within the aggregation regime. Here, we systematically explore the phase diagram of the globular protein BSA via its dynamics as a function of temperature $T$ and protein concentration $c_p$ as well as of the concentrations $c_s$ of trivalent salts YCl$_3$ and LaCl$_3$. By employing incoherent neutron backscattering spectroscopy at BASIS (SNS) with energy transfers up to 100 $\mu$eV, we unambiguously access the global and internal short-time self-diffusion of the protein clusters depending on $c_p,c_s$ and $T$. We determine the cluster size in terms of effective hydrodynamic radii as manifested by the cluster center-of-mass diffusion coefficients $D$. For both salts, we find a simple functional form $D(c_p,c_s,T)$ in the parameter range explored. The master-curve observed previously [1] can be confirmed also for different temperatures and different salts. The salt- specific calculated binding probabilities and inter-particle attraction strengths, based on the short-time microscopic diffusive properties, increase with salt concentration and temperature in the regimes investigated and can be linked to the macroscopic behavior and to microscopy data.

[1] M. Grimaldo et al. J. Phys. Chem. Lett. 6 (2015)

Primary author

Tilo Seydel (Institut Max von Laue - Paul Langevin)

Co-authors

Christian Beck (Institut Laue Langevin) Olga Matsarskaia Dr Michal Braun (Institut für angewandte Physik, Uni Tübingen) Mrs Lena Buehl (Institut für angewandte Physik, Universität Tübingen) Dr Niina H. Jalarvo (Spallation Neutron Source) Frank Schreiber (Institut für Angewandte Physik, Universität Tübingen, Germany)

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