Berlin 2015 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 40: Charged Soft Matter II
CPP 40.7: Vortrag
Mittwoch, 18. März 2015, 11:00–11:15, PC 203
Mechanisms underlying reentrant phase behavior of proteins: a model system — •Michal Braun1, Marcell Wolf1, Olga Matsarskaia1, Gudrun Lotze2, Fajun Zhang1, and Frank Schreiber1 — 1Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen — 2ESRF, Grenoble, France
Controlling and tuning the phase behavior of proteins is important in many areas such as structural biology including protein crystallization, pharmacology and biotechnology. One important effect in protein phase behavior is reentrant condensation (RC) which can be induced and controlled by multivalent ions ([1], [2], [3]). For example, YCl3 leads to RC in bovine serum albumin (BSA). This system features a macroscopic phase separation, which makes it difficult to study the mechanisms behind RC using scattering. LaCl3, on the other hand, induces cluster formation and RC in BSA without phase separation and the BSA-LaCl3 system is therefore highly suitable for the study of the physical mechanisms behind RC. Here, we discuss our findings from systematic SAXS and light scattering (LS) experiments as a function of both protein and salt concentrations. SAXS curves can be fitted using a sticky hard sphere model and the reentrant behavior is reflected in the stickiness parameter. LS helps to reveal the dependency of the cluster sizes on the interactions. These measurements thus provide detailed insights into the interactions in a system featuring RC. [1] Zhang et al., PRL, 101, 148101, 2008, [2] Zhang et al., Soft Matter, 8, 1313, 2012, [3] Roosen-Runge et al., PNAS, 108, 11815, 2011