High Apparent Dielectric Constants in the Interior of a Protein Reflect Water Penetration

Dwyer, John J.; Gittis, Apostolos G.; Karp, Daniel A.; Lattman, Eaton E.; Spencer, Daniel S.; Stites, Wesley E.; Garcia-Moreno, E.B.

doi:10.1016/s0006-3495(00)76411-3

Cited by 299 publications

(420 citation statements)

References 62 publications

(109 reference statements)

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“…Of course, the LCST of those systems involves hydrophobic collapse. In the present case, the lysozyme molecules are already folded and the dielectric constant of the surface should be significantly higher than for hydrophobically hydrated polymer molecules (55)(56)(57)(58).…”

Section: Salt Concentration (M)mentioning

confidence: 79%

The inverse and direct Hofmeister series for lysozyme

Zhang

Cremer

2009

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

391

542

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Anion effects on the cloud-point temperature for the liquid؊liquid phase transition of lysozyme were investigated by temperature gradient microfluidics under a dark field microscope. It was found that protein aggregation in salt solutions followed 2 distinct Hofmeister series depending on salt concentration. Namely, under low salt conditions the association of anions with the positively charged lysozyme surface dominated the process and the phase transition temperature followed an inverse Hofmeister series. This inverse series could be directly correlated to the size and hydration thermodynamics of the anions. At higher salt concentrations, the liquid-liquid phase transition displayed a direct Hofmeister series that correlated with the polarizability of the anions. A simple model was derived to take both charge screening and surface tension effects into account at the protein/water interface. Fitting the thermodynamic data to this model equation demonstrated its validity in both the high and low salt regimes. These results suggest that in general positively charged macromolecular systems should show inverse Hofmeister behavior only at relatively low salt concentrations, but revert to a direct Hofmeister series as the salt concentration is increased.liquid-liquid phase transition ͉ protein aggregation P rotein-protein interactions can lead to aggregation. Such intermolecular contacts underlie the mechanistic basis for a variety of diseases (1-4) and are key to protein crystallization (5-7). An effective way to determine the strength of biomacromolecular interactions is to study the temperature-induced phase separation that occurs in concentrated protein solutions (8). When a concentrated protein solution is cooled below its cloud-point temperature, the system can separate into 2 coexisting liquid phases: 1 rich in protein and 1 poor. As coacervate droplets of the protein-rich phase grow, the solution turns cloudy (white) as a result of the scattering of visible light. Upon standing, the solution may completely separate by gravity into a protein-rich phase and a nearly pure aqueous phase above it. The temperature at which the initial cloud point occurs provides a simple physical measurement of the forces acting among biomacromolecules. Specifically, the higher the temperature at which the initial cloud point occurs, the stronger the putative attractive forces between the protein molecules should be.Dissolved salts in aqueous solutions have a strong influence on protein-protein interactions and the subsequent aggregated states which are formed. In fact, cloud-point temperatures typically follow a specific ion order according to the Hofmeister series (5,6,(9)(10)(11)(12)(13)(14). The relative effectiveness of anions to induce protein aggregation typically follows 1 of 2 trends depending on the pH of the solution (15, 16). Above a protein's isoelectric point, the macromolecule bears a net negative charge and a direct Hofmeister series is normally observed. In this case, chaotropes such as I Ϫ , ClO 4 Ϫ , and SCN Ϫ he...

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Section: Salt Concentration (M)mentioning

confidence: 79%

The inverse and direct Hofmeister series for lysozyme

Zhang

Cremer

2009

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

391

542

View full text Add to dashboard Cite

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“…42 The larger values are attributed to water or moisture leading to hydration and some water penetration. 39 For consistency with previous work, 23,39 we use a static dielectric constant of lysozyme given by ε p = 2. We might underestimate in this way ε p and thus overestimate the static contribution to the Hamaker constant A ν = 0 (Eq.…”

Section: A Refractive Indices and Static Dielectric Constantsmentioning

confidence: 99%

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

Gögelein

Wagner

Cardinaux

et al. 2012

The Journal of Chemical Physics

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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.

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“…On the contrary, the smaller DDG bind value obtained for the V654A mutant is in line with a replacement of a hydrophobic residue into another of smaller size. A vast amount of structural data on various mutant proteins from different groups (Matthews, 1993;Buckle et al, 1996;Dwyer et al, 2000;Takano et al, 2001) suggests that single-site amino-acid substitutions, especially in the case of conservative replacements, do not affect the global structure of proteins. In other words, mutant proteins usually retain overall structures that are very similar to those of their wild-type counterparts.…”

Section: Molecular Modelingmentioning

confidence: 99%

Functional analyses and molecular modeling of two c-Kit mutations responsible for imatinib secondary resistance in GIST patients

et al. 2006

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Imatinib-acquired resistance related to the presence of secondary point mutations has become a frequent event in gastrointestinal stromal tumors. Here, transient transfection experiments with plasmids carrying two different KIT-acquired point mutations were performed along with immunoprecipitation of total protein extracts, derived from imatinib-treated and untreated cells. The molecular mechanics/Poisson Boltzmann surface area computational techniques were applied to study the interactions of the wild-type and mutated receptors with imatinib at the molecular level. Biochemical analyses showed KIT phosphorylation in cells transfected with vectors carrying the specific mutant genes. Imatinib treatment demonstrated that T670I was insensitive to the drug at all the applied concentrations, whereas V654A was inhibited by 6 lM of imatinib. The modeling of the mutated receptors revealed that both substitutions affect imatinib-binding site, but to a different extent: T670I substantially modifies the binding pocket, whereas V654A induces only relatively confined structural changes. We demonstrated that T670I and V654A cause indeed imatinib-acquired resistance and that the former is more resistant to imatinib than the latter. The application of molecular simulations allowed us to quantify the interactions between the mutated receptors and imatinib, and to propose a molecular rationale for this type of drug resistance.

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High Apparent Dielectric Constants in the Interior of a Protein Reflect Water Penetration

Cited by 299 publications

References 62 publications

The inverse and direct Hofmeister series for lysozyme

The inverse and direct Hofmeister series for lysozyme

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

Functional analyses and molecular modeling of two c-Kit mutations responsible for imatinib secondary resistance in GIST patients

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