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Dresden 2011 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 10: Poster: Charged Soft Matter

CPP 10.2: Poster

Monday, March 14, 2011, 17:30–19:30, P2

Ion competition in protein solution studied with scattering techniques: SAXS, SLS and DLS — •Elena Jordan1,2, Fajun Zhang1, Marcus Hennig1,2, Ralf Schweins2, Tilo Seydel2, Felix Roosen-Runge1, Sara Leibfarth1, Frank Schreiber1, and Giovanna Fragneto21IAP, Universität Tübingen, Germany — 2ILL Grenoble, France

For advances in protein science a better understanding of the protein interaction is essential. The reentrant phase behavior of proteins, induced by multivalent counterions (Y3+), is a versatile example for protein-protein interactions in electrolyte solutions. At a certain YCl3 concentration, c*, the proteins phase separate and at a even higher concentration, c**, the proteins redissolve with inversed surface charge [1]. We studied the effect of added NaCl on the reentrant condensation of proteins using SAXS, static and dynamic light scattering. We found that c* and c** are shifted to higher YCl3 concentrations in the presence of NaCl. The decrease in the low q intensity of SAXS indicates that the attractive interaction around c* is reduced with NaCl. The monovalent ions screen the charges and stabilize the solution. Around c** the SAXS data show that the attractive interaction is enhanced upon adding NaCl. Light scattering data and simulations support the observations. We conclude, that a mixture of YCl3 and NaCl can be used to fine-tune the overall interaction and phase behavior of proteins.

[1] F. Zhang, et al. Phys. Rev. Lett. 101, 148101 (2008)

[2] F.Zhang, et al. Proteins Vol. 78, 3450 (2010)

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