A method is described for the rapid preparation of erythrotropin from commercially available fetal bovine serum. It consists of the reversed-phase extraction of fetal bovine serum using octadecylsilyl-silica cartridges followed by reversed-phase high-pressure liquid chromatography (HPLC). Further purification can be achieved by gel-permeation HPLC. Serum erythrotropin coelutes with erythrotropin I from fetal bovine intestine on reversed-phase HPLC. It has a molecular weight and an amino acid composition very similar to those reported for the intestinal erythrotropins. The easy preparation of serum erythrotropin with specific activities higher than commercially available erythropoietin preparations will facilitate the study of the physiological role of this factor in vivo and in vitro.
KEY WORDS: HPLC, peptides; cell culture media; growth factors; protein/enzyme purification; peptide hormones. ' Supported by Grant MA-6072 from the Medical Research Council of Canada. The author is Chercheur-Boursier of the Fonds de la recherche en sante du Qtkbec. PHI, porcine intestinal peptide; TFA, trifluoroacetic acid: 2 Abbreviations used: ODS-silica, octadecvlsilvl-silica; U, unit of activity as defined by the thymidine incorporation assay using step III sheep plasma erythropoietin as standard.