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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 18: Polyelectrolytes

CPP 18.2: Vortrag

Dienstag, 24. März 2009, 09:45–10:00, ZEU 114

Reentrant Condensation of Proteins in Solution Induced by Multivalent Ions — •Luca Ianeselli¹, Fajun Zhang¹, Robert M. J. Jacobs², Maximilian W. A. Skoda³, Christopher C. Martin⁴, Sylvain Prévost⁵, and Frank Schreiber¹ — ¹Institut für Angewandte Physik. Universität Tübingen, 72076 Tübingen, Germany — ²CRL, University of Oxford, UK — ³ISIS Rutherford Appleton Laboratory, UK — ⁴SRS, Daresbury, UK — ⁵Helmholtz Center Berlin

Proteins in aqueous solution in the presence of multivalent salt ions can exhibit reentrant condensation [1]. In order to address the dependencies of the phenomenon on protein structure and surface charge density we examined systematically different proteins and multivalent ions systems using UV-Vis spectroscopy and small angle scattering (SAS). Phase diagrams with similar features at the two critical concentrations as expected by the charge inversion theory [2] were determined for wide protein and salt concentration ranges. Positively charged proteins at neutral pH like lysozyme do not show reentrant behavior by using Y3+ as salt ions whereas negative proteins like BSA, OV or HSA do. Al3+ and the organic salt Spermine4+ do not induce reentrant condensation because of their too high and too low charge density respectively. Y3+ however induces reentrant condensation for 5 of the 6 analyzed proteins. Selected samples with fixed protein concentration were studied by SAS. The data analysis provides evidence of the changes in protein-protein interactions, from repulsive to attractive as a function of salt concentration. [1] F. Zhang, et al. Phys. Rev. Lett. 2008,101,148101 [2] A.Y. Grosberg, et al. Rev. Mod. Phys. 2002, 74, 329