Salt-steered partitioning of proteins in polymeric two-phase systems based on N,N-dimethylformamide

The polymeric two-phase (liquid liquid) system, based on N,N-dimethylformamide (DMFA) and the two polymers Ficoll and poly(ethylene glycol). has been investigated. The partitioning of the water-insoluble protein fraction, zein (from corn), was affected by the addition of various salts that were soluble in DMFA. The effect of the salts has been correlated to their partition coefficients. The data have been fitted to a theory for partitioning of polyelectrolytes in aqueous two-phase systems. The two-phase system has been used for partial fractionation of zein by counter-current distribution.