Abstract:
: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.
journal_name
Biotechnol Bioengjournal_title
Biotechnology and bioengineeringauthors
Fan W,Bakir U,Glatz CEdoi
10.1002/(sici)1097-0290(19980820)59:4<461::aid-bitsubject
Has Abstractpub_date
1998-08-20 00:00:00pages
461-70issue
4eissn
0006-3592issn
1097-0290pii
10.1002/(SICI)1097-0290(19980820)59:4<461::AID-BITjournal_volume
59pub_type
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