MOLECULAR-MASS OF PROTEINS AND THEIR PARTITIONING IN AQUEOUS 2-PHASE SYSTEMS

Twenty proteins with molecular masses between 10(4) and 10(6) were par titioned in aqueous dextran-poly(ethylene glycol) two-phase systems wi th either 0.1 M KC] or 0.1 M KCl plus 3 M NaCl. The partition coeffici ent of all proteins were higher in the system with 0.1 M KCl plus 3 M NaCl than in the system with 0.1 M KCl alone. The ratios between the p artition coefficients in the two systems were strongly correlated with the molecular masses of the proteins. This fact may be used for analy tical as well as preparative purposes.