Protein partitioning in PEG/dextran aqueous two‐phase systems

Abstract

Abstract Utilizing a modified form of the Flory‐Huggins theory of polymer solution thermodynamics, a generalized expression has been obtained for correlating protein partitioning in the polyethylene glycol (PEG)/dextran aqueous two‐phase systems. The expression relates the natural logarithm of the partition coefficient of the protein to the polymer concentration difference between the phases. The parameters of the relationship are a function of protein and phase forming polymer molecular weight, protein‐water, protein‐polymer and polymer‐water interaction parameters, and the electrostatic potential difference between the phases. The relationship was verified by partitioning 17 proteins covering a wide range of molecular weight in the tie lines of the above systems, along with data from the literature. This correlation will facilitate the selection and engineering scale‐up of aqueous two‐phase systems for biomolecule purification.