Proteins in solution:from X-ray scattering intensities to interaction potentials

Tardieu, A.; Verge, A. Le; Malfois, Marc; Bonneté, Françoise; Finet, Stéphanie; Riès-Kautt, Madeleine; Belloni, Luc

doi:10.1016/s0022-0248(98)00828-8

Cited by 196 publications

(226 citation statements)

References 18 publications

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“…This conclusion, by itself, is not new for it has been reached earlier by formulating numerical work incorporating short-range forces and screened electrostatics and comparing it with x-ray scattering 39,40 and liquid-liquid phase separation. [41][42][43] The merit of the current analysis is its transparency because it is analytical and it is based on a nonperturbative variational principle for general short-range potentials, so it may be readily generalized.…”

Section: Discussionmentioning

confidence: 88%

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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Section: Discussionmentioning

confidence: 88%

Optimized Baxter model of protein solutions: Electrostatics versus adhesion

Prinsen

Odijk

2004

The Journal of Chemical Physics

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“…The form factor was calculated (39)(40)(41) by averaging over all possible protein orientations by integrating over the angles and θ with and For the structure factor S(Q), either a mean spherical approximation accounting for electrostatic repulsions (42,43) or a square-well potential representing short-ranged attractions (44) was used, depending on the degree of protein neutralization by the surfactant (see below). The depth (∈′ ) 3.28k B T) and width (λ ) 1.033) of the square well were estimated from the van der Waals attractive potential (45) by equating the area in the "well" to that of the overall potential (van der Waals plus electrostatic) over the range of separation distances where the potential is attractive. The model fits were performed using the data analysis software and structure factors provided by NIST (triaxial form factor available from CTL upon request).…”

Section: Methodsmentioning

confidence: 99%

Photocontrol of Protein Folding: The Interaction of Photosensitive Surfactants with Bovine Serum Albumin

2004

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The photoresponsive interaction of light-sensitive azobenzene surfactants with bovine serum albumin (BSA) at neutral pH has been investigated as a means to control protein folding with light irradiation. The cationic azobenzene surfactant undergoes a reversible photoisomerization upon exposure to the appropriate wavelength of light, with the visible-light (trans) form of the surfactant being more hydrophobic than the UV-light (cis) form. As a consequence, the trans form exhibits enhanced interaction with the protein compared to the cis form of the surfactant, allowing photoreversible control of the protein folding/unfolding phenomena. Small-angle neutron-scattering (SANS) measurements are used to provide detailed information on the protein conformation in solution. A fitting of the protein shape to a lowresolution triaxial ellipsoid model indicates that three discrete forms of the protein exist in solution depending on the surfactant concentration, with lengths of approximately 90, 150, and 250 Å, respectively, consistent with additional dynamic light-scattering measurements. In addition, shape-reconstruction methods are applied to the SANS data to obtain relatively high-resolution conformation information. The results confirm that BSA adopts a heart-shaped structure in solution at low surfactant concentration, similar to the well-known X-ray crystallographic structure. At intermediate surfactant concentrations, protein elongation results as a consequence of the C-terminal portion separating from the rest of the molecule. Further increases in the surfactant concentration eventually lead to a highly elongated protein that nonetheless still exhibits some degree of folding that is consistent with the literature observations of a relatively high helical content in denatured BSA. The results clearly demonstrate that the visible-light form of the surfactant causes a greater degree of protein unfolding than the UV-light form, providing a means to control protein folding with light that, within the resolution of SANS, appears to be completely reversible.Protein folding is a remarkable process that affects nearly every aspect of biological function. The conformation of a protein in solution is generally a function of electrostatic, hydrogen-bonding, van der Waals, and hydrophobic interactions among the amino acid residues that all typically favor a folded conformation, overcoming the entropic penalty associated with this folding of the protein into a compact state. For a given amino acid sequence, the protein will often adopt a unique structure in solution, termed the native state, whereby the charged and polar amino acid groups are exterior and exposed to water, while the nonpolar moieties generally reside in the interior of the folded structure, protected from unfavorable solvent interactions. Protein unfolding can be induced by a variety of external conditions such as changes in pH (ionization of nonpolar residues), temperature (complex interplay between enthalpic and entropic effects), and pressure (a conse...

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“…Concretely, Lyklema justified this specific adsorption on changes in the configurational entropy of the water molecules adjacent to the solid surface after binding of the ion to the surface sites. Tardieu et al 44 also used the DLVO theory in protein crystallization studies, and they were obeyed to vary either the charge or the potential attraction to account the salt series. Our strategy aims in the same direction because DLVO interactions will be somehow modified by the presence of specific cations and anions.…”

Section: A Theoretical Approachmentioning

confidence: 99%

Hofmeister Effects in the Stability and Electrophoretic Mobility of Polystyrene Latex Particles

et al. 2003

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Specific ionic effects on numerous solid-aqueous solution interfaces have usually been ranked in the socalled Hofmeister series. Ion specificity has experimentally been manifested in many ways. In this work, the colloidal stability and electrophoretic mobility of three different polystyrene latex samples are analyzed in the presence of different electrolytes. The effects on their colloidal stability and electrokinetic behavior provoked by four anions (SO 4 2-, Cl -, NO 3 -, and SCN -) and three cations (NH 4 + , Na + , and Ca 2+ ) located in different positions in the Hofmeister series are shown. Some of these ions specifically modified the pair potential interaction of the colloidal particles yielding results not explained by the Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory. A modification in the repulsive electrostatic term of this theory is then proposed to consider the ionic specificity. In addition, general but qualitative explanations about the subjacent mechanisms involved in the Hofmeister effects are also summarized.

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Proteins in solution:from X-ray scattering intensities to interaction potentials

Cited by 196 publications

References 18 publications

Optimized Baxter model of protein solutions: Electrostatics versus adhesion

Optimized Baxter model of protein solutions: Electrostatics versus adhesion

Photocontrol of Protein Folding: The Interaction of Photosensitive Surfactants with Bovine Serum Albumin

Hofmeister Effects in the Stability and Electrophoretic Mobility of Polystyrene Latex Particles

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