Dresden 2017 – wissenschaftliches Programm
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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.