Phase equilibria and glass transition in colloidal systems with short-ranged attractive interactions: Application to protein crystallization

Foffi, Giuseppe; McCullagh, Gavin D.; Lawlor, Aonghus; Zaccarelli, Emanuela; Dawson, Kenneth A.; Sciortino, Francesco; Tartaglia, P.; Pini, Davide; Stell, G.

doi:10.1103/physreve.65.031407

Cited by 179 publications

(232 citation statements)

References 85 publications

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“…Indeed, controllable short-range attraction and long-range repulsion is central to self-assembly processes in biological systems, in particular, protein crystallization occurring in the attractive regime of interparticle interactions (31)(32)(33). Aggregation-prone proteins seem to exhibit a similar very deep attractive potential (Ϸ50 k B T) as opposed to stable globular proteins (24).…”

Section: Discussionmentioning

confidence: 99%

Absence of equilibrium cluster phase in concentrated lysozyme solutions

Shukla

Mylonas

Cola

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

178

201

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In colloidal systems, the interplay between the short range attraction and long-range repulsion can lead to a low density associated state consisting of clusters of individual particles. Recently, such an equilibrium cluster phase was also reported for concentrated solutions of lysozyme at low ionic strength and close to the physiological pH. Stradner et al. [(2004) Equilibrium cluster formation in concentrated protein solutions and colloids. Nature 432:492-495] found that the position of the low-angle interference peak in small-angle x-ray and neutron scattering (SAXS and SANS) patterns from lysozyme solutions was essentially independent of the protein concentration and attributed these unexpected results to the presence of equilibrium clusters. This work prompted a series of experimental and theoretical investigations, but also revealed some inconsistencies. We have repeated these experiments following the protein preparation protocols of Stradner et al. using several batches of lysozyme and exploring a broad range of concentrations, temperature and other conditions. Our measurements were done in multiple experimental sessions at three different high-resolution SAXS and SANS instruments. The lowionic-strength lysozyme solutions displayed a clear shift in peak positions with concentration, incompatible with the presence of the cluster phase but consistent with the system of repulsively interacting individual lysozyme molecules. Within the decoupling approximation, the experimental data can be fitted using an effective interparticle interaction potential involving short-range attraction and long-range repulsion. dynamic arrested state ͉ macromolecular solutions ͉ protein interactions ͉ small-angle scattering ͉ structure factor T he arrested dynamics of colloidal systems and protein solutions interacting via short-range interactions have been actively studied both theoretically and experimentally in recent years (1-4). The mode coupling theory and molecular dynamics (MD) simulations have successfully unified seemingly dissimilar dynamical arrest scenarios in colloidal systems (4, 5). In addition to the conventional glassy state induced by the packing constraints, the presence of short-range attraction leads to a different glassy behavior. The apparently diverse type of dynamical arrest, such as gelation, jamming, glassification or non-ergodicity transition, etc., found in attractive systems can be unified in terms of this attractive glass transition (3). As competing shortrange attraction and long-range repulsion are introduced, additional features are observed (5). In particular, at intermediate volume fractions, the colloidal particles can form an equilibrium cluster phase, which in turn stabilizes a low-density arrested state (6). This type of particle clustering process at low volume fractions has been observed for various colloidal systems (7-9).Although the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory successfully describes the microstructure and equilibrium phase behavior of charged colloidal systems ov...

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Section: Discussionmentioning

confidence: 99%

Absence of equilibrium cluster phase in concentrated lysozyme solutions

Shukla

Mylonas

Cola

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

178

201

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“…71 More recently, thermodynamic perturbation theory was used to understand the interplay between phase coexistence and the glass line. 38 If the perturbative approach is known to give quantitatively imprecise results near phase boundaries and near criticality, the method can be, in principle, applied to very general mixtures for which the convergence of integral-equation-based methods is still out of reach. Perturbation theory is thus well-suited to study the stability of the modeled asymmetric crystallin mixtures.…”

Section: Stability Of Binary Mixtures From Perturbation Theorymentioning

confidence: 99%

Colloidal Characterization and Thermodynamic Stability of Binary Eye Lens Protein Mixtures

et al. 2008

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We present a study of binary mixtures of eye lens crystallin proteins. A coarse-grained model of aqueous Rand γ-crystallin mixtures based on molecular dynamics simulations and SANS experiments is proposed. Thermodynamic perturbation theory is implemented to obtain the stability boundaries, or spinodal surface, of the binary mixture in the full parameter space. The stability of these high-concentration crystallin mixtures was found to depend on the R-γ attraction in a manner that is both extremely sensitive and nonmonotonic; stronger or weaker attraction resulted in a spectacularly enhanced instability. The relevance of these mechanisms as possible sources of the alteration of the spatial distribution of the lens proteins encountered in cataract disease is discussed.

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“…33,34 A possible reason for this is that the second regime of phase separation occurs at protein concentrations where the solution gels or crystallizes. 35 Neither of these phenomena are included in our model. However, we expect similar effects to be relevant to crystallization especially since the structure of crystals is largely determined by excluded-volume effects, 30 which includes effects related to changes in the size and shape of the proteins.…”

Section: Summary and Discussionmentioning

confidence: 99%

Self-crowding induced phase separation in protein dispersions

Stegen

Schoot

2015

The Journal of Chemical Physics

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The coupling between protein conformation, molecular volume, and solution phase behaviour is studied theoretically for a two-state, coarse-grained protein model in which protein molecules can reversibly switch between a native and a non-native excited state. In the model, native and non-native conformers are represented by perfect spheres with different hard-core diameters. We presume the larger, non-native species to attract each other through some unspecified potential. We find that at low concentrations the native state is stabilised energetically and that at high concentrations the native state is again stabilised but this time by self-crowding, i.e., a lack of free volume. These two regimes are separated by two first-order transitions from a region where the non-native conformational state is prevalent, stabilised by attractive interactions between the proteins. The calculated phase diagram is very sensitive to even quite small differences in particle volumes and has unusual features, including the loss of a critical point if the size difference is sufficiently large. C 2015 AIP Publishing LLC. [http://dx

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Phase equilibria and glass transition in colloidal systems with short-ranged attractive interactions: Application to protein crystallization

Cited by 179 publications

References 85 publications

Absence of equilibrium cluster phase in concentrated lysozyme solutions

Absence of equilibrium cluster phase in concentrated lysozyme solutions

Colloidal Characterization and Thermodynamic Stability of Binary Eye Lens Protein Mixtures

Self-crowding induced phase separation in protein dispersions

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