A rapid purification of rat alpha 1-foetoprotein by phase partition

The phase partition system dextran/polyethylene glycol (2 : 1, w/w) was chosen to separate rat alpha 1-foetoprotein from rat serum albumin, which is its main contaminant due to their having close physicochemical properties. The optimization of this method necessitated a systematic study of the behaviour of rat serum albumin in the system under consideration. This article describes the optimum conditions, in terms of pH, ionic strength and the concentration of polymer solutions, for the purification and recovery of alpha 1-foetoprotein. After a prepurification of rat foetal serum by CM-cellulose chromatography, a single partition step permitted the recovery of 15% of the total alpha 1-foetoprotein present in the rat serum. The purity of this alpha 1-foetoprotein was demonstrated by its binding parameters and by analytical gel electrophoresis.