Dresden 2020 – scientific programme

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BP: Fachverband Biologische Physik

BP 2: Focus: Phase Separation in Biological Systems I (joint session BP/CPP)

BP 2.4: Talk

Monday, March 16, 2020, 10:15–10:30, SCH A251

Phase separation in protein solutions – a colloid physics’ perspective — •Florian Platten and Stefan U. Egelhaaf — Condensed Matter Physics Laboratory, Heinrich Heine University, Düsseldorf, Germany

Protein solutions undergoing phase separation are relevant for physiological functions (e.g., intracellular compartmentalization), disease pathology (e.g., cataract and amyloid plaque formation), biopharmaceutical formulations (e.g., their solubility and aggregation stability), the tunable design of soft solids (e.g., food gels) as well as a non-classical route to crystallization. The metastable liquid-liquid phase separation of lysozyme solutions was studied in terms of their phase coexistence temperatures and static structure factors S(Q). If scaled by a property of dilute solutions, namely the second virial coefficient B₂, instead of temperature, the experimental binodals fall onto a master curve, which is similar to that of an adhesive hard-sphere fluid; i.e., the extended law of corresponding states holds for protein solutions. Accordingly, S(Q) of moderately concentrated solutions can be described by B₂ using Baxter’s model. The interactions between protein molecules – even in test tubes – are highly complex, i.e., patchy and directional. Nevertheless, coarse-grained colloid models provide effective descriptions. These simple models facilitate further insights into the physics of protein phase separation.