A modified extended UNIQUAC model for proteins

A modification of the extended UNIQUAC model is proposed for the description of the non-ideality of protein solutions. Here, the Staverman–Guggenheim combinatorial contribution used in extended UNIQUAC model is replaced by the Flory–Huggins term to take into account the size differences between the protein and solvent. This new model allows an excellent description of the activity coefficients in protein systems, for a large range of pH and ionic strengths, with a reduced number of parameters.