“On the Collander equation”: Protein partitioning in polymer/polymer aqueous two-phase systems

• Published in: Journal of Chromatography A 2008-05, Vol.1190 (1), p.39-43
• Main Authors: Madeira, Pedro P., Teixeira, José A., Macedo, Eugénia A., Mikheeva, Larissa M., Zaslavsky, Boris Y.
• Format: Article
• Language: English
• Subjects: Analytical, structural and metabolic biochemistry; Aqueous two-phase systems; Biological and medical sciences; Collander equation; Electrophoresis, Polyacrylamide Gel; Fundamental and applied biological sciences. Psychology; General aspects, investigation methods; Polymers - chemistry; Protein partitioning; Proteins; Proteins - chemistry; Water - chemistry
• ISSN: 0021-9673
• DOI: 10.1016/j.chroma.2008.03.003

Distribution coefficients of randomly selected proteins were measured in aqueous two-phase systems (ATPSs) formed by different combinations of Dextran-75 (Dex), Ficoll-70, polyethylene glycol-8000 (PEG), hydroxypropyl starch-100 (PES), and Ucon50HB5100 (Ucon, a random copolymer of ethylene glycol and propylene glycol) at particular polymer concentrations, all containing 0.15 M NaCl in 0.01 M phosphate buffer, pH 7.4. Most of the proteins in the PEG-Ucon system precipitated at the interface. In the other ATPSs, namely, PES-PEG, PES-Ucon, Ficoll-PEG, Ficoll-Ucon, and in Dex-PEG and Dex-Ucon described earlier the distribution coefficients for the proteins were correlated according to the solvent regression equation: ln K i = a io ln K o + b io , where K i and K o are the distribution coefficients for any protein in the ith and oth two-phase systems. Coefficients a io and b io are constants, the values of which depend upon the particular compositions of the two-phase systems under comparison.