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Contribution of protein charge to partitioning in aqueous two‐phase systems
Author(s) -
Fan Weiyu,
Bakir Ufuk,
Glatz Charles E.
Publication year - 1998
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/(sici)1097-0290(19980820)59:4<461::aid-bit9>3.0.co;2-e
Subject(s) - virial coefficient , phase (matter) , charge (physics) , chemical physics , aqueous solution , chemistry , charge density , polymer , lysozyme , materials science , thermodynamics , physics , organic chemistry , biochemistry , quantum mechanics
Protein partitioning in aqueous two‐phase systems based on phase‐forming polymers is strongly affected by the net charge of the protein, but a thermodynamic description of the charge effects has been hindered by conflicting results. Many of the difficulties could be because of problems in isolating electrochemical effects from other interactions of phase components. We explored charge effects on protein partitioning in poly(ethylene glycol)‐dextran two‐phase systems by using two series of genetically engineered charge modifications of bacteriophage T4 lysozyme produced in Escherichia coli. The two series, one in the form of charged‐fusion tails and the other in the form of charge‐change point mutations, provided matching net charges but very different polarity. Partition coefficients of both series were obtained and interfacial potential differences of the phase systems were measured. Multi‐angle laser light scattering measurements were also performed to determine second virial coefficients. A semi‐empirical model accounting for the roles of both charge and non‐charge effects on protein partitioning behavior is proposed, and the results predicted from the model are compared to the results from the experiments. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:461–470, 1998.