Protein interactions in solution are conveniently analysed with small angle X-ray scattering (SAXS). Such an analysis has shown that the addition of monovalent salt induces an additional attraction between macromolecules. A differential effect of the anions is observed, which follows the order of the Hofmeister series. Such experimental observations should be helpful to test the adequacy of theoretical models.
The Hofmeister effect as seen by SAXS in protein solutions.