Dresden 2011 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 9: Poster: Biopolymers and Biomaterials
CPP 9.6: Poster
Montag, 14. März 2011, 17:30–19:30, P2
Protein reentrant condensation induced by Fe3+ and Al3+ — •Felix Roosen-Runge1, Benjamin Heck1, Fajun Zhang1, Maximilian W. Skoda2, Robert Jacobs3, and Frank Schreiber1 — 1Institut für Angewandte Physik, Universität Tübingen — 2ISIS, Rutherford Appleton Laboratory, United Kingdom — 3Department of Chemistry, University of Oxford, United Kingdom
Several globular proteins has been found to show reentrant phase behavior upon adding the trivalent salt Y3+, i.e. they aggregate for intermediate salt concentrations but occur in stable solution both at high and low salt concentrations [1]. Here we report on results for the physiological salts Al3+ and Fe3+ for the model protein bovine serum albumin (BSA). From zeta potential measurements we observe a charge inversion driven by binding of salt ions on the protein surface, which clearly goes beyond the effect due to pH-change of the solution. Small-angle X-ray scattering (SAXS) provides further information on protein shape and interactions. We observe conformational changes for BSA at different salt conditions. While at low salt concentrations electrostatic repulsion dominates the interaction, this interaction is lost in the aggregation regime. For high salt concentrations charge stabilization is recovered. The findings imply a universality of the phenomenon of reentrant condensation in protein systems, pointing towards new paths of controlling the protein phase behavior.
[1] F. Zhang et al., Phys.Rev.Lett. 101, 148101 (2008); F. Zhang et al., Proteins 78, 3450 (2010)