Three-step purification of retinol-binding protein from rat serum

Rat serum retinol-binding protein has been purified to apparent homogeneity in high yield by a new procedure utilizing three simple steps: DEAE-cellulose chromatography at pH 6.0, Sephadex G-75 gel filtration in the presence of 3.0 M urea, and finally DEAE-cellulose chromatography at pH 8.3. The second step accomplished the dissociation and separation of retinol-binding protein from its complex with prealbumin; this represents a substantial improvement over published procedures, in which sample recycling and preparative polyacrylamide gel electrophoresis were necessary. The purified retinol-binding protein was characterized by molecular weight measurement, fluorescence spectra and immunological properties.