Dresden 2009 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 16: POSTERS Polyelectrolytes and Biological Systems

CPP 16.4: Poster

Dienstag, 24. März 2009, 14:00–16:30, P3

Controlling Protein Interfacial Affinities by Ionic and Non-Ionic CosolventsFlorian Evers1, Juny Koo2, Thomas Gutberlet3, Roland Steitz4, •Metin Tolan1, and Claus Czeslik21Fakultät Physik, TU Dortmund, 44221 Dortmund — 2Fakultät Chemie, TU Dortmund, 44221 Dortmund — 3Paul-Scherrer-Institut, CH-5232 Villigen — 4Helmholtz-Zentrum Berlin, 14109 Berlin

In a biological cell, proteins perform their functions in a highly complex environment comprising crowding and confinement effects as well as interactions with interfaces and cosolvents. Cosolvents can stabilize or destabilize proteins in solution. Here, we present recent studies on how ionic and non-ionic cosolvents affect the interfacial affinity and structure of proteins at hydrophilic and hydrophobic solid surfaces. RNase A at a silica-water and a polystyrene-water interface were used as model systems and studied by neutron and optical reflectometry. The degree of protein adsorption and the density profile of the adsorbed protein films were determined in the absence and the presence of cosolvents. In the case of the hydrophilic silica-water interface, both the protein stabilizing glycerol and the destabilizing urea cause a distinct reduction in the interfacial affinity of RNase A. At the hydrophobic polystyrene surface, two trends become apparent: The kosmotropic SO42− ion lowers the amount of adsorbed protein when it is present at sub-molar concentrations, whereas the chaotropic SCN ion significantly enhances the degree of protein adsorption at concentrations of a few moles per liter. The obtained results will be discussed in terms of the underlying effects of the cosolvents on the adsorption mechanisms.

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