Dresden 2017 – wissenschaftliches Programm
CPP 48.11: Poster
Mittwoch, 22. März 2017, 18:30–21:00, P2-OG1
The role of trivalent salts in protein nucleation and crystallization — Marcus Mikorski1, Andrea Sauter1, Fajun Zhang1, Benedikt Sohmen1, Ralph Maier1, Georg Zocher2, Thilo Stehle2, and •Frank Schreiber1 — 1Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany — 2IFIB, Tübingen, Germany
Crystal structures of proteins are essential for understanding protein function. However, crystallography of proteins depends on high quality crystals for diffraction and is therefore often a challenging task. Using the negatively charged protein human serum albumin, we developed a model system to study nucleation and crystallization pathways via theoretical modelling and SAXS and SANS meassurements. We found that in a reentrant condensation state diagram, for negatively charged globular proteins, there are two boundaries at which the probability for high quality crystals is high. Between these boundaries a phase separated regime occurs . This interaction can be tuned by using different trivalent salts (YCl3, LaCl3, CeCl3, GdCl3) and varying the solvent (D2O, H2O). Here, we present data on the influence of these salts on the effective protein-protein interactions and the phase behavior, the pathways of crystal growth and finally the location of metal ions in the crystal unit cell and their role in stabilizing the crystal structure. Crystals grown in different salt and solvent conditions have the same unit cell. Thereby we provide a toolbox for growth of high quality protein crystals for diffraction.
 Zhang et al. Pure & Appl. Chem. 2014, 86, 191-202