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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 6: Charged Soft Matter

CPP 6.10: Vortrag

Montag, 14. März 2011, 16:45–17:00, ZEU 160

Anomalous small angle X-ray scattering studies of multivalent cations binding and distribution in protein solution — •Baohu Wu¹, Fajun Zhang¹, Maximilian W.A. Skoda², Robert M.J. Jacobs³, Michael Sztucki⁴, and Frank Schreiber¹ — ¹Institut für Angewandte Physik, Universität Tübingen — ²ISIS, RAL, UK — ³CRL, University of Oxford, UK — ⁴ESRF, France

Charge-induced protein-protein interactions attract much attention due to their direct relation to protein crystallization and protein association related diseases. For the interaction of proteins by multivalent cations, which shows a re-entrant condensation phase behavior, the distribution of cations is crucial [1]. So far, anomalous Small Angle X-Ray Scattering (ASAXS) has provided the best way to study this issue by selecting the energies away and near the absorption edge of the target ions [2]. Here we studied protein solutions in the presence of YCl₃ in the re-entrant regime. The ASAXS experiments were performed at the ESRF using 12 different energies near the K-absorption edge of yttrium. Systematic measurements of Y³⁺ around the proteins show clearly visible ASAXS shifts in the scattered intensity. The pure resonant signal for the multivalent ion has been successfully separated using the matrix method. These data can prove vital for modeling protein-cation interactions and the mechanisms of the protein re-entrant condensation behavior. The results will be discussed with regard to the binding number and distribution of Y³⁺ within the diffusion zone. [1] F. Zhang, et al. Phys. Rev. Lett. 2008, 101, 148101. [2] M. Sztucki, et al. J. Appl. Cryst. 2010, 43, 1479.