On the Long-Range Attraction between Proteins Due to Nonadsorbing Polysaccharide

Tuinier, Remco; Brûlet, A.

doi:10.1021/bm0255544

Cited by 14 publications

(15 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Such simulations correctly predict how the depletion interaction depends on the degree of polymerization and concentration of polymer. In some cases, even a quantitative agreement between experimental data and theory was obtained (7)(8)(9). Other research has shown that the influence of polymer addition may not always be attractive; in solutions diluted with respect to polyethylene glycol (PEG), a repulsion interaction between proteins was observed (10,11).…”

Section: Introductionmentioning

confidence: 92%

See 1 more Smart Citation

Solubility of Lysozyme in Polyethylene Glycol-Electrolyte Mixtures: The Depletion Interaction and Ion-Specific Effects

Bončina

Reščič

Vlachy

2008

Biophysical Journal

View full text Add to dashboard Cite

The solubility of aqueous solutions of lysozyme in the presence of polyethylene glycol and various alkaline salts was studied experimentally. The protein-electrolyte mixture was titrated with polyethylene glycol, and when precipitation of the protein occurred, a strong increase of the absorbance at 340 nm was observed. The solubility data were obtained as a function of experimental variables such as protein and electrolyte concentrations, electrolyte type, degree of polymerization of polyethylene glycol, and pH of the solution; the last defines the net charge of the lysozyme. The results indicate that the solubility of lysozyme decreases with the addition of polyethylene glycol; the solubility is lower for a polyethylene glycol with a higher degree of polymerization. Further, the logarithm of the protein solubility is a linear function of the polyethylene glycol concentration. The process is reversible and the protein remains in its native form. An increase of the electrolyte (NaCl) concentration decreases the solubility of lysozyme in the presence and absence of polyethylene glycol. The effect can be explained by the screening of the charged amino residues of the protein. The solubility experiments were performed at two different pH values (pH = 4.0 and 6.0), where the lysozyme net charge was +11 and +8, respectively. Ion-specific effects were systematically investigated. Anions such as Br(-), Cl(-), F(-), and H(2)PO(4)(-) (all in combination with Na(+)), when acting as counterions to a protein with positive net charge, exhibit a strong effect on the lysozyme solubility. The differences in protein solubility for chloride solutions with different cations Cs(+), K(+), and Na(+) (coions) were much smaller. The results at pH = 4.0 show that anions decrease the lysozyme solubility in the order F(-) < H(2)PO(4)(-) < Cl(-) < Br(-) (the inverse Hofmeister series), whereas cations follow the direct Hofmeister series (Cs(+) < K(+) < Na(+)) in this situation.

show abstract

Section: Introductionmentioning

confidence: 92%

“…This interaction results in aggregation of protein molecules, which is sufficiently gentle for the proteins not to denature. Many studies have been reported, both experimental and theoretical, to elucidate this interaction (4)(5)(6)(7)(8)(9)(10)(11).…”

Section: Introductionmentioning

confidence: 99%

Solubility of Lysozyme in Polyethylene Glycol-Electrolyte Mixtures: The Depletion Interaction and Ion-Specific Effects

Bončina

Reščič

Vlachy

2008

Biophysical Journal

View full text Add to dashboard Cite

show abstract

“…The value of R g can certainly be used to indicate the size of a protein; however, when the unfolded protein is far from a globular shape, the R g value may not accurately reflect the volume of the protein, due to the distance bias factor r 2 of R g . Since the volume of a protein may be used to characterize the protein unfolding behavior by using the newly developed Ising model with a mean field approximation (Liang et al, 2003), we employed model simulation (Liu et al, 2005;Tuinier & Brulet, 2003) to directly extract the shape and volume occupied by lysozyme (including the water molecules of hydration) in aqueous solutions from the measured SAXS data.…”

Section: Introductionmentioning

confidence: 99%

Charge interaction and temperature effects on the solution structure of lysozyme as revealed by small-angle X-ray scattering

et al. 2007

View full text Add to dashboard Cite

We have studied the structure of lysozyme as influenced by solution environment using small‐angle X‐ray scattering (SAXS). With an ellipsoid form factor and a structure factor derived using the mean spherical approximation to account for the electrostatic repulsion of lysozyme, we have extracted detailed structural information about the protein in aqueous solutions, including the size, shape, and net charge number. The SAXS data analysis shows that lysozyme in pure water, expressing an averaged net charge number of ~6, folds to an ellipsoid‐like shape with a radius of gyration Rg = 16.6 Å. Temperature‐dependent SAXS for lysozyme in a buffer solution in which charge repulsion has been eliminated suggests that the protein may thermally unfold gradually along a preferred direction from the ellipsoidal shape with an aspect ratio of p≃ 2 at 303 K to an elongated shape with p≃ 3 at 343 K. The structural parameters of the unfolded lysozyme obtained using model fitting are compared with the envelope morphology simulated using a dummy‐residues model. From the evolution of the volume of lysozyme during the thermal unfolding process, we deduce a free‐energy profile for the protein thermally unfolded in water using a modified Ising model on the basis of a mean field approximation.

show abstract

“…According to the first ͑model 1͒, the protein molecule was pic-tured as a hard sphere of radius R p = 15 Å, with a charge Z p = 0, or +5 in the center. 28 Lysozyme is a globular protein with 32 residues that may ionize in a solvent. 11 and 41͒, they do not provide good descriptions of protein molecules.…”

Section: Model and Methodsmentioning

confidence: 99%

“…28 The measurements were performed in 0.10 mol/ dm 3 phosphate buffer at pH = 6.0, where lysozyme had a net charge Z p = + 9. The experimental data in the form of the scattered intensity were apply to lysozyme-dextran mix-tures, and were obtained using SANS.…”

Section: Comparison With Experimentsmentioning

confidence: 99%

Computer simulations and theoretical aspects of the depletion interaction in protein-oligomer mixtures

Bončina

Reščič

Kalyuzhnyi

et al. 2007

The Journal of Chemical Physics

View full text Add to dashboard Cite

The depletion interaction between proteins caused by addition of either uncharged or partially charged oligomers was studied using the canonical Monte Carlo simulation technique and the integral equation theory. A protein molecule was modeled in two different ways: either as (i) a hard sphere of diameter 30.0 A with net charge 0, or +5, or (ii) as a hard sphere with discrete charges (depending on the pH of solution) of diameter 45.4 A. The oligomers were pictured as tangentially jointed, uncharged, or partially charged, hard spheres. The ions of a simple electrolyte present in solution were represented by charged hard spheres distributed in the dielectric continuum. In this study we were particularly interested in changes of the protein-protein pair-distribution function, caused by addition of the oligomer component. In agreement with previous studies we found that addition of a nonadsorbing oligomer reduces the phase stability of solution, which is reflected in the shape of the protein-protein pair-distribution function. The value of this function in protein-protein contact increases with increasing oligomer concentration, and is larger for charged oligomers. The range of the depletion interaction and its strength also depend on the length (number of monomer units) of the oligomer chain. The integral equation theory, based on the Wertheim Ornstein-Zernike approach applied in this study, was found to be in fair agreement with Monte Carlo results only for very short oligomers. The computer simulations for a model mimicking the lysozyme molecule (ii) are in qualitative agreement with small-angle neutron experiments for lysozyme-dextran mixtures.

show abstract

On the Long-Range Attraction between Proteins Due to Nonadsorbing Polysaccharide

Cited by 14 publications

References 32 publications

Solubility of Lysozyme in Polyethylene Glycol-Electrolyte Mixtures: The Depletion Interaction and Ion-Specific Effects

Solubility of Lysozyme in Polyethylene Glycol-Electrolyte Mixtures: The Depletion Interaction and Ion-Specific Effects

Charge interaction and temperature effects on the solution structure of lysozyme as revealed by small-angle X-ray scattering

Computer simulations and theoretical aspects of the depletion interaction in protein-oligomer mixtures

Contact Info

Product

Resources

About