title: Protein partition coefficients can be estimated efficiently by hybrid shortcut calculations.
abstract: The extraction of therapeutic proteins like monoclonal antibodies in aqueous two-phase systems (ATPS) is a suitable alternative to common cost intensive chromatographic purification steps within the downstream processing. Thereby the protein partitioning can be selectively changed using a displacement agent (additional salt) in order to allow for a successful purification of the target protein. Within this work a new shortcut strategy for the calculation of protein partition coefficients in polymer-salt ATPS is presented. The required protein-solute (phase-forming component, displacement agent) interactions are covered by the cross virial coefficient B23 measured by composition gradient multi-angle light scattering (CG-MALS). Using this shortcut calculation allows for an efficient determination of the partition coefficients of the target protein immunoglobulin G (IgG) and the impurity human serum albumin (HSA) within PEG-citrate and PEG-phosphate ATPS independently on the protein concentration. We demonstrate that the selection of a suitable displacement agent allowing for a selective purification of IgG from HSA is accessible by B23. Based on the determination of the protein-protein interactions via CG-MALS covered by the second osmotic virial coefficient B22 a further optimization of ATPS preventing protein precipitation is enabled. The results show that our approach contributes to an efficient downstream processing development.
authors.affiliation: Technische Universität Dortmund, Department of Biochemical and Chemical Engineering, Laboratory of Thermodynamics, Dortmund, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Kress
authors.affiliation: Technische Universität Dortmund, Department of Biochemical and Chemical Engineering, Laboratory of Thermodynamics, Dortmund, Germany.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Sadowski
authors.affiliation: Technische Universität Dortmund, Department of Biochemical and Chemical Engineering, Laboratory of Thermodynamics, Dortmund, Germany. Electronic address: christoph.brandenbusch@bci.tu-dortmund.de.
authors.forename: Christoph
authors.initials: C
authors.lastname: Brandenbusch
mesh_terms: D005591:Chemical Fractionation / Q000379:methods*; D011232:Chemical Precipitation; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry / Q000302:isolation & purification; D008956:Models, Chemical; D011092:Polyethylene Glycols / Q000737:chemistry; D011506:Proteins / Q000737:chemistry* / Q000302:isolation & purification*; D012709:Serum Albumin / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D007074:Immunoglobulin G; D011506:Proteins; D012709:Serum Albumin; D011092:Polyethylene Glycols
keywords: Aqueous two-phase extraction; Immunoglobulin G; Protein partitioning; Protein precipitation