Berlin 2015 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 8: Colloids and Complex Liquids II (joint session CPP, BP, DY)

CPP 8.12: Vortrag

Montag, 16. März 2015, 18:00–18:15, C 130

A systematic study of the influence of trivalent metal ions on phase behaviour in protein solutions — •Olga Matsarskaia¹, Michal Braun¹, Andrea Sauter¹, Marcell Wolf¹, Roland Roth², Fajun Zhang¹, and Frank Schreiber¹ — ¹Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen — ²Institut für Theoretische Physik, Universität Tübingen

Thermodynamic phenomena such as reentrant condensation (RC) and liquid-liquid phase separation (LLPS) are involved in various protein-related processes, e.g. protein condensation diseases and protein crystallisation. We could show that these transitions are inducible in protein solutions using various trivalent cations [1], [2]. In this work, the influence of cation size on such phase behaviour in bovine serum albumin (BSA) was studied systematically in the presence of salts with increasing cation sizes (YbCl₃, YCl₃, GdCl₃, CeCl₃ and LaCl₃). The results reveal that charge inversion, the prerequisite of RC and LLPS in these systems, is found independent of cation size. Interestingly, however, salt concentration ranges in which macroscopic LLPS is observed decrease with increasing cations: while Yb³⁺ leads to the largest LLPS area, Ce³⁺ features the smallest one. La³⁺, the largest cation studied, induces RC, but does not lead to LLPS at all. The findings thus indicate that the size of cations present in the environment of a protein influences the strength of protein-cation interactions and therefore plays an important role in phase transitions of the protein.

[1] Zhang et al (2008). Phys. Rev. Lett., 101(14), 148101; [2] Zhang et al (2012). Soft Matter, 8, 1313-1316.