title: Investigation and prediction of protein precipitation by polyethylene glycol using quantitative structure-activity relationship models.
abstract: Precipitation of proteins is considered to be an effective purification method for proteins and has proven its potential to replace costly chromatography processes. Besides salts and polyelectrolytes, polymers, such as polyethylene glycol (PEG), are commonly used for precipitation applications under mild conditions. Process development, however, for protein precipitation steps still is based mainly on heuristic approaches and high-throughput experimentation due to a lack of understanding of the underlying mechanisms. In this work we apply quantitative structure-activity relationships (QSARs) to model two parameters, the discontinuity point m* and the β-value, that describe the complete precipitation curve of a protein under defined conditions. The generated QSAR models are sensitive to the protein type, pH, and ionic strength. It was found that the discontinuity point m* is mainly dependent on protein molecular structure properties and electrostatic surface properties, whereas the β-value is influenced by the variance in electrostatics and hydrophobicity on the protein surface. The models for m* and the β-value exhibit a good correlation between observed and predicted data with a coefficient of determination of R2≥0.90 and, hence, are able to accurately predict precipitation curves for proteins. The predictive capabilities were demonstrated for a set of combinations of protein type, pH, and ionic strength not included in the generation of the models and good agreement between predicted and experimental data was achieved.
authors.affiliation: Institute of Engineering in Life Sciences, Section IV: Biomolecular Separation Engineering, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany. Electronic address: frank.haemmerling@kit.edu.
authors.forename: Frank
authors.initials: F
authors.lastname: Hämmerling
authors.affiliation: Institute of Engineering in Life Sciences, Section IV: Biomolecular Separation Engineering, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany.
authors.forename: Christopher
authors.initials: C
authors.lastname: Ladd Effio
authors.affiliation: Institute of Engineering in Life Sciences, Section IV: Biomolecular Separation Engineering, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Andris
authors.affiliation: Institute of Engineering in Life Sciences, Section IV: Biomolecular Separation Engineering, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Kittelmann
authors.affiliation: Institute of Engineering in Life Sciences, Section IV: Biomolecular Separation Engineering, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany. Electronic address: juergen.hubbuch@kit.edu.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Hubbuch
mesh_terms: D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000302:isolation & purification; D011232:Chemical Precipitation; D057927:Hydrophobic and Hydrophilic Interactions; D008956:Models, Chemical; D011092:Polyethylene Glycols / Q000737:chemistry*; D011506:Proteins / Q000737:chemistry / Q000302:isolation & purification; D021281:Quantitative Structure-Activity Relationship; D055672:Static Electricity
chemical_list: D000911:Antibodies, Monoclonal; D011506:Proteins; D011092:Polyethylene Glycols
keywords: Monoclonal antibody; Polyethylene glycol; Precipitation; Quantitative structure–activity relationship (QSAR); Semi-mechanistic modeling