Affinity partitioning: Development of mathematical model describing behavior of biomolecules in aqueous two-phase systems

A mathematical model describing the affinity partitioning of macromolecules in aqueous two-phase systems has been derived. The model was used to calculate binding parameters that were compared against values deter mined by means of ultracentrifugation and fluorescence titration. The mathematical model and its modifications were found to describe satisfactorily the partition behavior of macromolecules with differing numbers of binding sites. It could be shown that in solutions containing PEG the binding behavior of FDH is changed fundamentally. The dissociation constants of FDH with PEG-blue in the presence and absence of PEG are different.