Use of immobilized lectins and other ligands for partial purification of erythropoietin

The ability of a variety of affinity adsorbents to isolate erythropoietin (Ep) from contaminating proteins in crude preparations of the hormone was examined. Of 13 lectin-agarose derivatives, 6 bound EP but only 2, wheat germ agglutinin (WGA) and phytohemagglutinin (PHA), bound the hormone quantitatively. The extent to which PHA bound Ep depended on the isolectin composition of the PHA. The leukoagglutinating form (L-PHA) failed to bind the hormone completely, while the erythroagglutinating form (E-PHA) had such a high affinity for Ep that it could be released only with 4 M guanidine hydrochloride (pH 7.0). PHA-P, which contains both the E and L isolectins, bound Ep quantitatively, and the hormone could be partially released by either N-acetylgalactosamine or sialic acid. Ep bound to WGA-agarose could be partially released with N-acetylglucosamine or sialic acid; with N,N-diacetylchitobiose recovery was quantitive. Two adsorbents, Cibacron Blue F3GA and octylsuccinic anhydride, which have a high afinity for albumin, a major contaminant of crude Ep preparations, also bound Ep quantitatively. Agarose-bound antialbumin IgG, however, was effective in removing albumin from crude hormone preparations without adsorbing a significant quantity of Ep. Neither agarose-bound neuraminidase nor hydrophobic interaction chromatography employing agarose coated with substituted or unsubstituted hydrocarbon chains separated Ep from contaminating proteins in crude preparations of the hormone.