Regensburg 2013 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 20: Poster: Colloids and Complex Liquids
CPP 20.28: Poster
Dienstag, 12. März 2013, 18:15–20:15, Poster C
On the Formation of Clusters in Protein Solutions Upon Addition of Multivalent Ions — •Daniel Soraruf1, Fajun Zhang1, Felix Roosen-Runge1, Tilo Seydel1, Ralf Schweins2, and Frank Schreiber2 — 1Institut für Angewandte Physik, Tübingen — 2ILL, Grenoble, France
Formation of clusters of proteins in solution are currently of strong fundamental interest, and also of enormous practical interest, from amyloidogenic diseases to food and pharma industry. Current research focuses on the mechanism of protein clustering, its role in phase transitions, the lifetime and stability of clusters. We investigate protein solutions of bovine serum albumin (BSA) with YCl3. The system exhibits a reentrant transition, characterized by the boundaries c* and c** for the concentration of Y3+ ions; in between the system is in a condensed regime[1]. We study the formation of clusters approaching c* by means of SLS/DLS, obtaining information about diffusion coefficient, compressibility, and size of the clusters[2]. A continuous decrease in diffusion coefficient and increase in overall scattered intensity reveal the formation of aggregates of 100 nm in solution, which are stable over days. The inverse forward scattering intensity decreases linearly over a broad salt concentration range and the compressibility diverges close to c*. Results from different protein concentrations can be rescaled into a master curve as a function of normalized csalt/c*. The formation of the clusters could be related to charge balance and patchy attraction of the proteins. [1] F. Zhang et al., PRL 101, 2008, 148101;[2] Roosen-Runge et al., PNAS 108,2012, 11815.