title: Purification of two forms of colony-stimulating factor from mouse L-cell-conditioned medium.
abstract: A modified procedure for the purification of the colony-stimulating factors (CSFs) in mouse L-cell-conditioned medium is used to isolate two forms of CSF, which are separable by reversed-phase high performance liquid chromatography with 300-A pore size supports. The specific biological activity of these CSFs (2 X 10(9) colonies/mg) was considerably higher than has been achieved by other methods. Even at high concentration (200 pM) both molecules stimulated predominantly more macrophage than granulocyte colonies; however, the less hydrophobic form appeared to stimulate the formation of more pure granulocytic colonies. Almost twice as much of the less hydrophobic CSF was recovered from L-cell-conditioned medium. Analysis using sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that both forms of L-cell CSF had apparent molecular masses of approximately 70,000 daltons. However, on reduction with 2-mercaptoethanol, while both forms generated a 39,000-dalton subunit, the less hydrophobic form also yielded a 32,000-dalton subunit. Storage of either form of L-cell CSF at pH 2.1, in the presence of acetonitrile or isopropanol, destroyed the biological activity. Electrophoretic analysis of the L-cell CSFs stored under these conditions indicated that this was associated with a spontaneous dissociation of the CSF dimer into the inactive subunits. There was some charge heterogeneity (pI 3.5-4.7) indicating different degrees of glycosylation. The unique N-terminal amino acid sequences of both forms of CSF were the same: (Lys-Glu-Val-Ser-Glu-His-X-Ser-His-Met-Ile-Gly-Asn). Thus, the polypeptide chains appear to be identical for the subunits of both forms of L-cell CSF.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D003115:Colony-Stimulating Factors / Q000302:isolation & purification*; D003470:Culture Media; D004591:Electrophoresis, Polyacrylamide Gel; D005347:Fibroblasts / Q000032:analysis; D007525:Isoelectric Focusing; D051379:Mice; D008970:Molecular Weight
chemical_list: D000596:Amino Acids; D003115:Colony-Stimulating Factors; D003470:Culture Media