Preparation of electrophoretic variants of corticosteroid-binding globulin (CBG) using liquid liquid partition chromatography

Human corticosteroid-binding globulin (CBG) was purified to homogeneity by application of three different chromatographic methods. After fractionation of pregnancy serum with ammonium sulfate the 80%-pellet was used for affinity chromatography based on tresyl activated Sepharose (Pharmacia, Uppsala, Sweden). The affinity eluate was injected into a Mono Q anion exchange column (Pharmacia). Fractions containing CBG were finally purified by liquid liquid chromatography on LiParGel 750 (Merck, Darmstadt, F.R.G.). The purified protein was characterized by IEF and PAGE. This paper describes a method for the chromatographic separation of the two variants of CBG without a loss of binding activity towards steroids for each of the two characteristic bands of this protein.