Effects of Crowding, Osmolytes, Temperature and Pressure on the Interaction Potential of Dense Protein Solutions

Abstract

We studied the effect of pressure on the structure and intermolecular interactions of dense lysozyme solutions in various cosolvent mixtures and upon addition of various Hofmeister anions using small-angle X-ray scattering in combination with liquid-state theoretical approaches [1-3]. Supplementary thermodynamic information was obtained by employing calorimetric techniques, densitometry and ultrasound velocimetry. We show that the particular structural properties of water and specific ion effects play a crucial major role in protein stabilisation, notably under high hydrostatic pressure conditions. Also the effect of confinement on the solvational properties and intermolecular interaction of proteins was studied, including the effects of self-crowding and macromolecular crowders on the temperature-pressure stability diagram of proteins [4]. We also discuss the effect of pressure on the second virial coefficient and how pressure can be used to control and fine-tune protein crystallization. Moreover, we present results on the phase behavior of dense lysozyme solutions in the liquid-liquid phase separation region. A re-entrant liquid-liquid phase separation region has been discovered at elevated pressures, which originates in the pressure dependence of the solvent-mediated protein-protein interactions [3].[1] M. A. Schroer, J. Markgraf, D. C. F. Wieland, C. J. Sahle, J. Moller, M. Paulus, M. Tolan, R. Winter, Phys. Rev. Lett. 106 (2011) 178102[2] M. A. Schroer, Y. Zhai, D. C. F. Wieland, C. J. Sahle, J. Nase, M. Paulus, M. Tolan, R. Winter, Angew. Chem. Int. Ed. 50 (2011) 11413[3] J. Moller, S. Grobelny, J. Schulze, S. Bieder, A. Steffen, M. Erlkamp, M. Paulus, M. Tolan, R. Winter, Phys. Rev. Lett. 112 (2014) 028101[4] M. Erlkamp, S. Grobelny, R. Winter, Phys. Chem. Chem. Phys. 16 (2014) 5965