title: 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.
authors.affiliation: Istituto di Scienze Fisiche, Università di Ancona, and INFM Unità di Ancona, I-60131 Ancona, Italy. f.spinozzi@alisf1.unian.it
authors.forename: Francesco
authors.initials: F
authors.lastname: Spinozzi
authors.forename: Domenico
authors.initials: D
authors.lastname: Gazzillo
authors.forename: Achille
authors.initials: A
authors.lastname: Giacometti
authors.forename: Paolo
authors.initials: P
authors.lastname: Mariani
authors.forename: Flavio
authors.initials: F
authors.lastname: Carsughi
mesh_terms: D000818:Animals; D001703:Biophysics / Q000379:methods; D007782:Lactoglobulins / Q000737:chemistry; D008892:Milk / Q000737:chemistry; D015233:Models, Statistical; D009010:Monte Carlo Method; D011485:Protein Binding; D011506:Proteins / Q000737:chemistry*; D012542:Scattering, Radiation; D013053:Spectrophotometry; D013816:Thermodynamics; D014965:X-Rays
chemical_list: D007782:Lactoglobulins; D011506:Proteins