Interaction of Proteins in Solution from Small-Angle Scattering: A Perturbative Approach

Abstract

In this work an improved methodology for studying interactions of proteins in solution by small-angle scattering is presented. Unlike the most common approach, where the protein-protein correlation functions g(ij)(r) are approximated by their zero-density limit (i.e., the Boltzmann factor), we propose a more accurate representation of g(ij)(r) that takes into account terms up to the first order in the density expansion of the mean-force potential. This improvement is expected to be particularly effective in the case of strong protein-protein interactions at intermediate concentrations. The method is applied to analyze small-angle x-ray scattering data obtained as a function of the ionic strength (from 7 to 507 mM) from acidic solutions of beta-lactoglobulin at the fixed concentration of 10 gl(-1). The results are compared with those obtained using the zero-density approximation and show significant improvement, particularly in the more demanding case of low ionic strength.

Combining structure and dynamics: non-denaturing high-pressure effect on lysozyme in solution

“…The hard-sphere potential plainly depends on the average protein radius, R, which in simple terms can be related to lysozyme molecular volume that, increasing pressure, varies according to protein compressibility (Kundrot & Richards 1987;Katrusiak & Dauter 1996;Fourme et al 2001). The Coulombic screened potential depends on the number Z of charges per protein, on the dielectric constant of the medium 1 (which is known to increase as a function of pressure (Floriano & Nascimento 2004)) and on the ionic strength of the solution I S (Spinozzi et al 2002). According to previous data (Gruner 2004), the protein charge is not expected to be largely affected by high pressure, at least if unfolding events do not occur.…”

Protein‐protein interactions as a target for drugs in proteomics

“…The methods for investigation of protein-protein interaction based on physicochemical approaches, including site directed mutagenesis or chemical modification of amino acid groups participating in such interaction, were discussed in many early reviews [58][59][60][61]. Here bioinformatic and functional proteomic methods allowing us to predict and validate protein complexes formation are discussed.…”

Preferential solvation of lysozyme in water/ethanol mixtures

“…(11) in Ref. 37). Concerning the attractive Yukawian term, the preexponential constant is written as A 2 = −2R J, where J is the so-called potential at protein-protein contact, whereas the constant κ 2 is simply written as the inverse of the decay length d.…”