title: Hofmeister challenges: ion binding and charge of the BSA protein as explicit examples.
abstract: Experiments on bovine serum albumin (BSA) via potentiometric titration (PT) and electrophoretic light scattering (ELS) are used to study specific-ion binding. The effect is appreciable at a physiological concentration of 0.1 M. We found that anions bind to the protein surface at an acidic pH, where the protein carries a positive charge (Z(p) > 0), according to a Hofmeister series (Cl(-) < Br(-) < NO(3)(-) < I(-) < SCN(-)), as well as at the isoionic point (Z(p) = 0). The results obtained require critical interpretation. The measurements performed depend on electrostatic theories that ignore the very specific effects they are supposed to reveal. Notwithstanding this difficulty, we can still infer that different 1:1 sodium salts affect the BSA surface charge/pH curve because anions bind to the BSA surface with an efficiency which follows a Hofmeister series.
authors.affiliation: Department of Chemical and Geological Sciences, University of Cagliari-CSGI and CNBS, Cittadella Universitaria, S.S. 554 bivio Sestu, 09042 Monserrato (CA), Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Medda
authors.forename: Brajesh
authors.initials: B
authors.lastname: Barse
authors.forename: Francesca
authors.initials: F
authors.lastname: Cugia
authors.forename: Mathias
authors.initials: M
authors.lastname: Boström
authors.forename: Drew F
authors.initials: DF
authors.lastname: Parsons
authors.forename: Barry W
authors.initials: BW
authors.lastname: Ninham
authors.forename: Maura
authors.initials: M
authors.lastname: Monduzzi
authors.forename: Andrea
authors.initials: A
authors.lastname: Salis
mesh_terms: D000818:Animals; D002417:Cattle; D004586:Electrophoresis; D006863:Hydrogen-Ion Concentration; D007477:Ions / Q000378:metabolism; D008027:Light; D008958:Models, Molecular; D011199:Potentiometry; D011485:Protein Binding; D011487:Protein Conformation; D012492:Salts / Q000737:chemistry / Q000378:metabolism; D012542:Scattering, Radiation; D012710:Serum Albumin, Bovine / Q000737:chemistry* / Q000378:metabolism*; D012964:Sodium / Q000737:chemistry / Q000378:metabolism
chemical_list: D007477:Ions; D012492:Salts; D012710:Serum Albumin, Bovine; D012964:Sodium