Regensburg 2013 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 20: Poster: Colloids and Complex Liquids
CPP 20.27: Poster
Dienstag, 12. März 2013, 18:15–20:15, Poster C
Immunoglobulin G in Solution with Polyethylene Glycol: Protein Interaction and Phase Transitions — •Bo Jing1, Anastasia Dietrich1, Saliba Barsaume1, Fajun Zhang1, Michael Sztucki2, and Frank Schreiber1 — 1Institute of Applied Physics, University of Tübingen — 2ESRF, Grenoble, France
Immunoglobulin G (IgG) plays a crucial role in the immune response by interacting with the proteins of pathogens. In addition, the interaction of IgG with itself and the resulting liquid-liquid phase separation (LLPS) or crystallization is also of great interest, e.g. for the understanding of cryoglobulinemia and for pharmaceutical applications. In these cases, it is desirable to control the phase behaviour of IgG in solution. We achieve this through the addition of polyethylene glycol (PEG) to bovine plasma IgG solutions, which allows us to tune the range and strength of short-range attractive interactions between IgG molecules. We measured the IgG PEG solutions by small-angle X-ray scattering (SAXS) and we observed a significant dependence of the interaction on IgG concentration, PEG molecular weight and concentration as well as temperature. The two-Yukawa potential is used to fit our data, and the so obtained potential parameters are associated with the detailed phase diagrams which we compiled over the same four parameters. Thereby, we identify quantitative conditions on the interaction potential under which phase transitions occur in IgG PEG solutions. These findings allow us to assess the significance of specific, anisotropic interactions between IgG molecules in the explanation of the observed SAXS data and macroscopic phase behaviour.