Effect of glycerol and dimethyl sulfoxide on the phase behavior of lysozyme: Theory and experiments

Abstract

Salt, glycerol, and dimethyl sulfoxide (DMSO) are used to modify the properties of protein solutions. We experimentally determined the effect of these additives on the phase behavior of lysozyme solutions. Upon the addition of glycerol and DMSO, the fluid-solid transition and the gas-liquid coexistence curve (binodal) shift to lower temperatures and the gap between them increases. The experimentally observed trends are consistent with our theoretical predictions based on the thermodynamic perturbation theory and the Derjaguin-Landau-Verwey-Overbeek model for the lysozyme-lysozyme pair interactions. The values of the parameters describing the interactions, namely the refractive indices, dielectric constants, Hamaker constant and cut-off length, are extracted from literature or are experimentally determined by independent experiments, including static light scattering, to determine the second virial coefficient. We observe that both, glycerol and DMSO, render the potential more repulsive, while sodium chloride reduces the repulsion.

Soft matter perspective on protein crystal assembly

“…Phase diagrams for about a dozen proteins, including lysozyme, γ-crystallin, insulin, and myoglobin, have been experimentally determined under different solution conditions [52][53][54][55][56][57][58]. Intriguingly, these phase diagrams have in common a topology that is qualitatively different from that of simple liquids ( Fig.…”

“…Most saliently for protein assembly, patchiness further lowers the metastable critical point, stabilizes open geometries such as diamond and cubic crystals, and qualitatively changes the shape of the gas-liquid coexistence region (Table I) [107,118]. This last point is interesting because experimental phase diagrams of proteins, such as lysozyme and γ-crystallin, have a binodal whose width and critical packing fraction are much smaller than those of isotropic models [53,58,104]. Although patchiness requires the specification of more model parameters and results in a certain loss of universality [107,119], it also weakens high-order correlations in the fluid structure, which enables the use of relatively simple liquid-state descriptions, such as Wertheim's theory, for their analysis [59,[120][121][122][123][124][125].…”

Electrokinetic and hydrodynamic properties of charged-particles systems

“…The stimuli-dependent size and biocompatibility of microgels such as poly (N-isopropylacrylamide) (PNiPAm) allows for their use in biomedical applications including drug delivery. Experimentally well-studied examples of globular proteins are, e.g., bovine serum albumin (BSA), lyzoyzme, and apoferritin [1][2][3][4][5][6]. If dispersed in water, the proteins are moderately charged, by an amount depending on temperature, pH value, salinity, and protein concentration.…”

Self-Consistent Ornstein-Zernike Approximation (SCOZA) and exact second virial coefficients and their relationship with critical temperature for colloidal or protein suspensions with short-ranged attractive interactions

“…On the other hand, the attractive and repulsive Yukawa potentials may be related to the screened Coulomb interactions occurring in ionic solutions, and by this reason they have often been employed in models for protein suspensions. [22][23][24] Within the framework of the studies on very short-ranged attractions, the SW model was investigated through Monte Carlo (MC) computer simulations by Bolhuis et al, 25 López-Rendón et al, 26 and recently by Largo et al 27 The SCOZA integral equation was applied to the SW potential by Schöll-Paschinger et al 20 as well as by Pini et al 21 As regards the HSY model, many studies -using mainly MC simulations -focused on the relationship between the phase behavior and the range of the attractive potential. 10,25,[28][29][30] The SCOZA approach was employed by Foffi et al, 31 Orea et al, 32 and by Valadez-Peréz et al 24 The paper by Orea et al 32 has been our main source of both MC and SCOZA numerical data for the HSY model.…”