Affinity purification of cellular retinoic acid-binding protein on 14-carboxy-13-cis-retinamide-sepharose 4B

Affinity-based separations and purifications. Patents and literature

The separation and purification of biologically functional molecules (e.g., proteins, antibodies, peptides, hormones, low molecular weight biologicals) is of fundamental importance to biotechnology. Affinity separations have become a particularly attractive method for bioseparations due to their high degree of selectivity. Numerous affinity ligands have been prepared in recent years including lectins, nucleic acids, inhibitors, and immunoresponse agents. Furthermore, a variety of novel supports have been synthesized to aid in the development of commercially useful affinity separation systems. Recent US patents and scientific literature on affinity separations and purifications are surveyed. Patent abstracts are summarized individually and a list of literature references are given.

Affinity purification of retinoic acid-binding proteins using immobilized 4-(2-hydroxyethoxy)retinoic acid

An affinity chromatographic matrix that purifies cellular retinoic acid-binding protein to near homogeneity from rat testes cytosol has been developed. The three-step procedure includes an acid precipitation, a batch treatment with CM Bio-Gel, and affinity chromatography on 4-(2-hydroxyethoxy)retinoic acid coupled to epoxy-activated Sepharose 6B. The binding protein was purified approximately 8500-fold based on total soluble testicular protein and with a recovery in excess of 80%. In addition, further enhancement of the purity of the protein can be attained by size-exclusion HPLC to increase purification to 21,000-fold. The recovered protein has an apparent M(r) 14,300 as determined by size-exclusion HPLC and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The protein is isolated in the apo-form and retains its ability to bind retinoic acid as evidenced by the binding of [3H]retinoic acid. An apparent retinoic acid-binding protein of M(r) 18,000 has also been isolated from rat testes nuclei by the affinity chromatography step. The affinity phase has been used for 6 months without any detectable loss in its ability to purify cellular retinoic acid-binding protein.