title: Disulfide arrangement of human insulin-like growth factor I derived from yeast and plasma.
abstract: The disulfide arrangement of yeast derived human insulin-like growth factor I (yIGF-I) was determined using a combination of Staphylococcus aureus V8 protease mapping, fast-atom-bombardment mass spectrometry as well as amino acid sequence and composition analysis. Three disulfide bridges were found between the following cysteine residues: Cys6-Cys48, Cys47-Cys52 and Cys18-Cys61. IGF-I isolated from human plasma (pIGF-I) was found to have an identical disulfide configuration. A yeast-derived isomeric form of IGF-I (yisoIGF-I) exhibited an altered disulfide arrangement: Cys6-Cys47, Cys48-Cys52 and Cys18-Cys61. Radioreceptor analysis of pIGF-I and yIGF-I showed high specific activity, 20,000 U/mg. However, yisoIGF-I demonstrated a severely reduced ability to bind to the IGF-I receptor (19%) and was less potent in provoking a mitogenic response in Balb/C 3T3 fibroblasts (50% at doses 10-100 ng/ml). The data demonstrate the importance of correct disulfide arrangement in IGF-I for full biological activity.
authors.affiliation: Kabi Pharmacia Peptide Hormones, Stockholm, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Axelsson
authors.forename: S
authors.initials: S
authors.lastname: Johansson
authors.forename: G
authors.initials: G
authors.lastname: Eketorp
authors.forename: H
authors.initials: H
authors.lastname: Zazzi
authors.forename: B
authors.initials: B
authors.lastname: Hemmendorf
authors.forename: P
authors.initials: P
authors.lastname: Gellerfors
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D003553:Cystine / Q000032:analysis / Q000737:chemistry; D004247:DNA / Q000096:biosynthesis; D004220:Disulfides / Q000737:chemistry*; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D011869:Radioligand Assay; D011994:Recombinant Proteins / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D012697:Serine Endopeptidases / Q000378:metabolism; D016339:Spectrometry, Mass, Fast Atom Bombardment; D014357:Trypsin / Q000378:metabolism
chemical_list: D004220:Disulfides; D010446:Peptide Fragments; D011994:Recombinant Proteins; D003553:Cystine; D007334:Insulin-Like Growth Factor I; D004247:DNA; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase; D014357:Trypsin