A versatile viscometric method for the study of dissolved proteins, exemplified for casein micelles in ammoniacal solutions

Abstract Viscosities of casein solutions were measured within the dilute range in ammoniacal water and in saline solvents containing different amounts and different kinds of salt. All these data are modeled quantitatively by means of an approach accounting for the polyelectrolyte character of casein micelles. Two parameters are required: The intrinsic viscosity [ η ] and a viscometric interaction parameter β . The behavior of casein is compared with that of chain-like polyelectrolytes. For both polymers one observes a pronounced reduction of [ η ] with increasing salt concentration. However, for casein the decline of [ η ] is less pronounced by more than an order of magnitude and depends on…