SKM 2023 – wissenschaftliches Programm

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SYSD: Symposium SKM Dissertation Prize 2023

SYSD 1: SKM Dissertation Prize

SYSD 1.1: Hauptvortrag

Montag, 27. März 2023, 09:30–10:00, HSZ 04

Diffusion of antibodies in solution: from individual proteins to phase separation domains — •Anita Girelli — Universität Tübingen, Tübingen, Germany — Stockholm University, Stockholm, Sweden

We investigated the diffusion of a model system for liquid-liquid phase separation (LLPS), which is a biological mechanism for the formation of intracellular organelles. The solution of γ-globulin and PEG spontaneously separates and reaches a gel state due to the high concentration of the more concentrated of the two phases. The hierarchy of motions requires to probe the sample from nanometers to micrometers and time scales from picoseconds to hundreds of seconds. We achieved this by combining light, neutron, and X-ray scattering. At LLPS domains length scale, X-ray photon correlation spectroscopy (XPCS) reveals correlation functions which show typical characteristics of ballistic motion as seen for colloidal gels [1]. The experimental results are compared with simulated data based on the Cahn-Hilliard equation. Qualitative comparability is obtained by adding a strong dependence of the protein mobility on protein concentration. The validity of this assumption is confirmed by probing the diffusion on the protein length scale and below with neutron quasi-elastic scattering and XPCS [2,3]. The combination of Neutron Spin Echo and XPCS allows to access the diffusion at protein length scale over 10 orders of magnitude.

[1] Girelli et al., PRL 126 (13), 2021. [2] Girelli et al., Mol. Pharm. 18 (11), 2021.[3] Reiser et al., Nat. Comm., 13,2022.