Diffusion Properties of the Ternary System Human Serum Albumin–Sodium Cholate–Water

The four diffusion coefficients of the ternary system human serum albumin (HSA,1)–sodium cholate (NaC,2)–water (W,0) were determined at three average compositions with constant protein concentration, C 1 o , and variable bile salt concentration, C 2 . Various types of solute–solute interactions are present in this ternary system: electrostatic, co-ions–protein, and unspecific volume interactions due to the large difference in size of the two solutes. Each type of interaction has a different effect in determining the values and the sign of the experimental diffusion coefficients, exp D ij . To simplify the analysis of the dependence of the exp D ij s on C 2 , we considered three model systems where different types of solute–solute interaction are present individually. The overall analysis allows highlighting which kinds of solute–solute interaction predominates in determining the value of each diffusion coefficient.