Extended law of corresponding states for protein solutions

Abstract

The so-called extended law of corresponding states, as proposed by Noro and Frenkel [J. Chem. Phys. 113, 2941 (2000)], involves a mapping of the phase behaviors of systems with short-range attractive interactions. While it has already extensively been applied to various model potentials, here we test its applicability to protein solutions with their complex interactions. We successfully map their experimentally determined metastable gas-liquid binodals, as available in the literature, to the binodals of short-range square-well fluids, as determined by previous as well as new Monte Carlo simulations. This is achieved by representing the binodals as a function of the temperature scaled with the critical temperature (or as a function of the reduced second virial coefficient) and the concentration scaled by the cube of an effective particle diameter, where the scalings take into account the attractive and repulsive contributions to the interaction potential, respectively. The scaled binodals of the protein solutions coincide with simulation data of the adhesive hard-sphere fluid. Furthermore, once the repulsive contributions are taken into account by the effective particle diameter, the temperature dependence of the reduced second virial coefficients follows a master curve that corresponds to a linear temperature dependence of the depth of the square-well potential. We moreover demonstrate that, based on this approach and cloud-point measurements only, second virial coefficients can be estimated, which we show to agree with values determined by light scattering or by Derjaguin-Landau-Verwey-Overbeek (DLVO)-based calculations.

Dynamics of liquid-liquid phase separation of wheat gliadins

“…To compare gliadins with others proteins, we calculate the reduced second virial coefficient B 2 * = B 2 / B 2, HS , with B 2, HS the second virial coefficient of the equivalent hard sphere. B 2, HS is equal to 2/3 πσ eff 3 with σ eff the effective diameter accounting for hard core and electrostatic repulsion 60 , 61 . The effective radius of gliadins is about 3.3 +/−0.3 nm as determined in Supplementary data 2 based on our previous results of osmotic compressibility 27 .…”

Effect of the surface charge distribution on the fluid phase behavior of charged colloids and proteins

“…105,106 In fact, many theoretical models do require incorporation of charge-charge interactions for adequately fit experimental liquid-liquid binodal curves. 106,107 Interestingly, if one considers the average size of a globular protein (~ 4 nm), those PLFs with broad coexistence curves and similar values for the dipole moment (e.g., triangles and squares in Figs. 6 and 7) qualitatively capture the main characteristics of experimental protein phase behavior.…”

Self-assembly of trimer colloids: effect of shape and interaction range

“…26 Originally proposed by Noro and Frenkel for isotropic particles exhibiting macroscopic phase separation, ECS is a useful way to draw comparisons between models and identify which ones are essentially equivalent. 26,27 Foffi and Sciortino found that patchy particles also obey ECS near the gas-liquid critical point. 28 In addition, ECS has been used to study the phase behavior of active particle suspensions.…”