“Sticky hard spheres” model of proteins near crystallization: A test based on the osmotic compressibility of lysozyme solutions

Piazza, Roberto; Peyre, Véronique; Degiorgio, Vittorio

doi:10.1103/physreve.58.r2733

Cited by 76 publications

(89 citation statements)

References 15 publications

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“…We also point out that the parameter is not the thermodynamic temperature in the usual sense. Even if temperature is the relevant parameter in an experimental realization of adhesive hard spheres, its relation to depends entirely on the substance, and could be linear, 27 inverse, 28 or more complicated. 5 Table II and Fig.…”

Section: A Coexistence Curvementioning

confidence: 99%

Phase diagram of the adhesive hard sphere fluid

Miller¹,

Frenkel

2004

The Journal of Chemical Physics

143

185

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The phase behavior of the Baxter adhesive hard sphere fluid has been determined using specialized Monte Carlo simulations. We give a detailed account of the techniques used and present data for the fluid-fluid coexistence curve as well as parametrized fits for the supercritical equation of state and the percolation threshold. These properties are compared with the existing results of Percus-Yevick theory for this system.

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Section: A Coexistence Curvementioning

confidence: 99%

Phase diagram of the adhesive hard sphere fluid

Miller¹,

Frenkel

2004

The Journal of Chemical Physics

143

185

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“…We have employed the substitution u 2 ϭs 2 ϩt 2 Ϫ2st cos , with the angle between x 12 and x 13 . Using the expression for g(x) ͓Eq.…”

Section: Appendix C: Corrections To the Free Energymentioning

confidence: 99%

“…10 In recent years, there has been a tendency to forget about all details of the protein interaction altogether-both attractive and repulsive-and to introduce a single adhesion parameter. [10][11][12][13][14] Despite the electrostatic repulsion which is substantial, the data are often merely rationalized in terms of the bare protein diameter within the context of an adhesive sphere model and such an approach seems to have merit. [10][11][12][13][14] This empiricism has prompted us to develop a theory of screened charged protein spheres that have a constant stickiness, but where the electrostatic interaction is compensated, in part, by the adhesive forces.…”

Section: Introductionmentioning

confidence: 99%

“…[10][11][12][13][14] Despite the electrostatic repulsion which is substantial, the data are often merely rationalized in terms of the bare protein diameter within the context of an adhesive sphere model and such an approach seems to have merit. [10][11][12][13][14] This empiricism has prompted us to develop a theory of screened charged protein spheres that have a constant stickiness, but where the electrostatic interaction is compensated, in part, by the adhesive forces. Thus, we argue that, effectively, the spheres are assigned a hard diameter identical to the actual diameter provided the remnant adhesive interaction now depends on the electrolyte and protein concentrations in a manner to be determined variationally.…”

Section: Introductionmentioning

confidence: 99%

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Optimized Baxter model of protein solutions: Electrostatics versus adhesion

Prinsen

Odijk

2004

The Journal of Chemical Physics

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A theory is set up of spherical proteins interacting by screened electrostatics and constant adhesion, in which the effective adhesion parameter is optimized by a variational principle for the free energy. An analytical approach to the second virial coefficient is first outlined by balancing the repulsive electrostatics against part of the bare adhesion. A theory similar in spirit is developed at nonzero concentrations by assuming an appropriate Baxter model as the reference state. The first-order term in a functional expansion of the free energy is set equal to zero which determines the effective adhesion as a function of salt and protein concentrations. The resulting theory is shown to have fairly good predictive power for the ionic-strength dependence of both the second virial coefficient and the osmotic pressure or compressibility of lysozyme up to about 0.2 volume fraction.

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“…In fact, Baxter's solution is often used to to analyze experimental results for systems as diverse as silica suspensions [8], copolymer micelles [9], and the fluid phase of lysozyme [10].…”

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confidence: 99%

Competition of Percolation and Phase Separation in a Fluid of Adhesive Hard Spheres

2003

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Using a combination of Monte Carlo techniques, we locate the liquid-vapor critical point of adhesive hard spheres. We find that the critical point lies deep inside the gel region of the phase diagram. The (reduced) critical temperature and density are τc = 0.1133 ± 0.0005 and ρc = 0.508 ± 0.01. We compare these results with the available theoretical predictions. Using a finite-size scaling analysis, we verify that the critical behavior of the adhesive hard sphere model is consistent with that of the 3D Ising universality class.PACS numbers: 61.20.Ja, 64.70.Ja The structure of a simple liquid is well described by that of a system of hard spheres at the same effective density. To a good approximation, the effect of attractive interactions on the liquid structure can be ignored. This feature of simple liquids is implicit in the Van der Waals theory for the liquid-vapor transition, and has been made explicit in the highly successful thermodynamic perturbation theories for simple liquids [1]. The perturbation approach becomes exact as the range of the attractive interaction tends to infinity while its integrated strength remains constant [3]. We refer to this limit as the 'Van der Waals' (VDW) limit [2]. Conversely, as the attractive forces become shorter-ranged and stronger, the perturbation approach is likely to break down. Fluids with strong, short-ranged attraction (so-called 'energetic' fluids [4]) are of growing importance in the area of complex liquids. For example, short-range attractions are thought to be responsible for the transition from a 'repulsive' to an 'attractive' glass [4], which has recently been observed experimentally in PMMA (polymethylmethacrylate) dispersions [6].In this Letter, we consider a model system that can be considered as the prototypical energetic fluid: a fluid of adhesive hard spheres (AHS). Introduced in 1968 [7], the AHS model is a reference system for particles with short range attractions. The pair potential consists of an impenetrable core plus a surface adhesion term that favors configurations where spheres are in contact. At larger separations, there is no interaction. The AHS model can be considered as the 'anti Van der Waals' limit.Baxter showed [7] that the Percus-Yevick (PY) equation can be solved analytically for adhesive hard spheres. In fact, Baxter's solution is often used to to analyze experimental results for systems as diverse as silica suspensions [8], copolymer micelles [9], and the fluid phase of lysozyme [10].One important feature of the AHS model is that its phase diagram contains a liquid-vapor coexistence region [11]. The PY equation offers different routes to estimate the location of the liquid-vapor critical point. However, the 'compressibility route' [7] and the 'energy route' [12] lead to estimates for the critical temperature that differ by some 20%, while the estimates for the critical density differ by almost a factor of three. For the analysis of experimental data, it is important to know the location of the critical point more accurately. The ...

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“Sticky hard spheres” model of proteins near crystallization: A test based on the osmotic compressibility of lysozyme solutions

Cited by 76 publications

References 15 publications

Phase diagram of the adhesive hard sphere fluid

Phase diagram of the adhesive hard sphere fluid

Optimized Baxter model of protein solutions: Electrostatics versus adhesion

Competition of Percolation and Phase Separation in a Fluid of Adhesive Hard Spheres

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