title: Solubilization of proteins in aqueous two-phase extraction through combinations of phase-formers and displacement agents.
abstract: The aqueous two-phase extraction (ATPE) of therapeutic proteins is a promising separation alternative to cost-intensive chromatography, still being the workhorse of nowadays downstream processing. As shown in many publications, using NaCl as displacement agent in salt-polymer ATPE allows for a selective purification of the target protein immunoglobulin G (IgG) from human serum albumin (HSA, represents the impurity). However a high yield of the target protein is only achievable as long as the protein is stabilized in solution and not precipitated. In this work the combined influence of NaCl and polyethylene glycol (Mw=2000g/mol) on the IgG-IgG interactions was determined using composition gradient multi-angle light scattering (CG-MALS) demonstrating that NaCl induces a solubilization of IgG in polyethylene glycol 2000 solution. Moreover it is shown that the displacement agent NaCl has a significant and beneficial influence on the IgG solubility in polyethyleneglycol2000-citrate aqueous two-phase system (ATPS) which can also be accessed by these advanced B22measurements. By simultaneous consideration of IgG solubility data with results of the ATPS phase behavior (especially volume fraction of the respective phases) allows for the selection of process tailored ATPS including identification of the maximum protein feed concentration. Through this approach an ATPS optimization is accessible providing high yields and selectivity of the target protein (IgG).
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: D007074:Immunoglobulin G / Q000737:chemistry* / Q000302:isolation & purification; D011092:Polyethylene Glycols / Q000737:chemistry; D012709:Serum Albumin / Q000737:chemistry* / Q000302:isolation & purification; D012995:Solubility; D014867:Water
chemical_list: D007074:Immunoglobulin G; D012709:Serum Albumin; D014867:Water; D011092:Polyethylene Glycols
keywords: Aqueous two-phase extraction; Downstream processing; Protein interactions; Protein partitioning; Protein solubilization