The Effect of Ionic Strength, Temperature, and Pressure on the Interaction Potential of Dense Protein Solutions: From Nonlinear Pressure Response to Protein Crystallization

Abstract

Understanding the intermolecular interaction potential, V(r), of proteins under the influence of temperature, pressure, and salt concentration is essential for understanding protein aggregation, crystallization, and protein phase behavior in general. Here, we report small-angle x-ray scattering studies on dense lysozyme solutions of high ionic strength as a function of temperature and pressure. We show that the interaction potential changes in a nonlinear fashion over a wide range of temperatures, salt, and protein concentrations. Neither temperature nor protein and salt concentration lead to marked changes in the pressure dependence of V(r), indicating that changes of the water structure dominate the pressure dependence of the intermolecular forces. Furthermore, by analysis of the temperature, pressure, and ionic strength dependence of the normalized second virial coefficient, b2, we show that the interaction can be fine-tuned by pressure, which can be used to optimize b2 values for controlled protein crystallization.

Intermolecular interactions in highly concentrated protein solutions upon compression and the role of the solvent

“…[67][68][69][70][71] The application of pressure leads to an anisotropic compression along the axis of the unit cell, i.e., a compression of the a axis, whereas the c axis length stays approx- imately constant. 25 These data are in good agreement with pressure dependent measurements on lysozyme crystals. 68 Interestingly, the intensity of the Bragg peaks decreases upon compression, which indicates suppression of protein crystallization upon hydrostatic compression of the solution.…”

“…45 A width of the attractive part of V Y (r) of d = 0.3 nm was used. 25 From the fits to the experimental data, the depth of the attractive part of the interaction potential, J (Eq. (6)), was obtained.…”

“…This parameter space and the underlying intermolecular interaction potential of the proteins as a function of these parameters are hardly explored today. 13,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] The use of the pressure variable is least understood so far and is hence in the focus of this study.…”

High Pressure Bioscience

“…The resulting SAXS signal can be described, within the so-called decoupling approximation, as product of the form factor P(q) and an effective structure factor (Schroer et al 2011a;Möller et al 2012) S eff .q/ D 1 C hF .q/i 2 P .q/ .S.q/ 1/ : The resulting SAXS signal can be described, within the so-called decoupling approximation, as product of the form factor P(q) and an effective structure factor (Schroer et al 2011a;Möller et al 2012) S eff .q/ D 1 C hF .q/i 2 P .q/ .S.q/ 1/ :…”

“…The latter parameter was explored in a few studies only, such as on subtilisin, glucose isomerase, thaumatin, SNase, RNase A, and lysozyme (Webb et al 1999;Visuri et al 1990;Waghmare et al 2000;Crisman and Randolph 2010;Kadri et al 2003Kadri et al , 2005Jaenicke 1991, 1993;Schall et al 1994;Saikumar et al 1995;Lorber et al 1996;Takano et al 1997;Suzuki et al 2002aSuzuki et al ,b, 2005Nagatoshi et al 2003;Möller et al 2012Möller et al , 2014bJavid et al 2007a, b). The latter parameter was explored in a few studies only, such as on subtilisin, glucose isomerase, thaumatin, SNase, RNase A, and lysozyme (Webb et al 1999;Visuri et al 1990;Waghmare et al 2000;Crisman and Randolph 2010;Kadri et al 2003Kadri et al , 2005Jaenicke 1991, 1993;Schall et al 1994;Saikumar et al 1995;Lorber et al 1996;Takano et al 1997;Suzuki et al 2002aSuzuki et al ,b, 2005Nagatoshi et al 2003;Möller et al 2012Möller et al , 2014bJavid et al 2007a, b).…”