title: Interactions of lysozyme in concentrated electrolyte solutions from dynamic light-scattering measurements.
abstract: The diffusion of hen egg-white lysozyme has been studied by dynamic light scattering in aqueous solutions of ammonium sulfate as a function of protein concentration to 30 g/liter. Experiments were conducted under the following conditions: pH 4-7 and ionic strength 0.05-5.0 M. Diffusivity data for ionic strengths up to 0.5 M were interpreted in the context of a two-body interaction model for monomers. From this analysis, two potential-of-mean-force parameters, the effective monomer charge, and the Hamaker constant were obtained. At higher ionic strength, the data were analyzed using a model that describes the diffusion coefficient of a polydisperse system of interacting protein aggregates in terms of an isodesmic, indefinite aggregation equilibrium constant. Data analysis incorporated multicomponent virial and hydrodynamic effects. The resulting equilibrium constants indicate that lysozyme does not aggregate significantly as ionic strength increases, even at salt concentrations near the point of salting-out precipitation.
authors.affiliation: Department of Chemical Engineering, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: D E
authors.initials: DE
authors.lastname: Kuehner
authors.forename: C
authors.initials: C
authors.lastname: Heyer
authors.forename: C
authors.initials: C
authors.lastname: Rämsch
authors.forename: U M
authors.initials: UM
authors.lastname: Fornefeld
authors.forename: H W
authors.initials: HW
authors.lastname: Blanch
authors.forename: J M
authors.initials: JM
authors.lastname: Prausnitz
mesh_terms: D000645:Ammonium Sulfate; D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D002645:Chickens; D004058:Diffusion; D004573:Electrolytes; D005260:Female; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008027:Light; D046911:Macromolecular Substances; D008956:Models, Chemical; D009113:Muramidase / Q000737:chemistry*; D009994:Osmolar Concentration; D012542:Scattering, Radiation; D012996:Solutions; D014867:Water
chemical_list: D004573:Electrolytes; D046911:Macromolecular Substances; D012996:Solutions; D014867:Water; D009113:Muramidase; D000645:Ammonium Sulfate