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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 42: Charged Soft Matter, Ionic Liquids and Polyions I

CPP 42.4: Vortrag

Mittwoch, 22. März 2017, 15:45–16:00, ZEU 114

Cation-induced hydration effects cause lower critical solution temperature behavior in protein solutions — •Olga Matsarskaia¹, Michal K. Braun¹, Felix Roosen-Runge², Marcell Wolf¹, Fajun Zhang¹, Roland Roth³, and Frank Schreiber¹ — ¹Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen — ²Institut Laue-Langevin, Grenoble, France — ³Institut für Theoretische Physik, Universität Tübingen

Systems consisting of negatively charged proteins and trivalent salts feature strong short-range attractive forces and exhibit a rich phase behaviour including reentrant condensation, clustering and crystallisation [1]. Here, we report a lower critical solution temperature liquid-liquid phase separation (LCST-LLPS) behaviour in a system of bovine serum albumin (BSA) and the trivalent salt YCl₃. Combining isothermal titration calorimetry (ITC) and ζ potential data into a comprehensive model, we show that cation-protein binding is an endothermic and thus entropy-driven process. We attribute the entropic contribution to a partial release of hydration water molecules around Y³⁺ cations and protein carboxyl groups. Our findings have implications for the general understanding of hydration-mediated interactions of soft matter.

[1] Zhang et al. Pure & Appl. Chem. 2014, 86, 191-202; [2] Matsarskaia et al. JPCB 2016, 120, 7731-7736.