Berlin 2018 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 4: Complex Fluids and Colloids I (joint session CPP/DY)

CPP 4.5: Vortrag

Montag, 12. März 2018, 10:30–10:45, C 264

Interactions in Protein Solutions in the Vicinity of the Gas-Liquid Binodal — •Jan Hansen¹, Florian Platten¹, Jannik Nedergaard Pedersen², Jan Skov Pedersen², and Stefan U. Egelhaaf¹ — ¹Condensed Matter Physics Laboratory, Heinrich Heine University, Düsseldorf, Germany — ²Department of Chemistry & iNANO, Aarhus University, Denmark

Intermolecular interactions in protein solution depend on a delicate balance of electrostatic, van der Waals and hydrophobic interactions, hydration and other specific contributions. Under certain conditions, short-ranged attractions dominate. Then, proteins can be described as adhesive hard spheres, i.e. their equilibrium phase diagram contains a solubility line below which the metastable gas-liquid binodal is submerged. Here, we examine in how far effective interaction models from colloid science can help to rationalize the phase behavior and interactions of protein solutions in the vicinity of the gas-liquid binodal. For different solution compositions, binodals have been determined by cloud-point measurements, yielding estimates of the critical temperature T_c. The effective structure factor of protein solutions has been determined for various protein concentrations and temperatures by small-angle X-ray scattering. The data is well described by a one-parameter fit based on Baxter’s model, from which the second virial coefficient B₂ is inferred. If plotted as a function of temperature normalized by T_c, the values of B₂ follow a universal behaviour for various solution conditions, as suggested by the extended law of corresponding states.