title: 1H-NMR assignment and secondary structure of human insulin-like growth factor-I (IGF-I) in solution.
abstract: Human insulin-like growth factor-I (IGF-I) was studied by two-dimensional 1H-NMR spectroscopy. Resonance assignments were obtained for all the backbone protons and almost all of the sidechain protons of the total 70 amino acid residues, using sequence-specific assignment procedures. The secondary structure elements of human IGF-I were identified by investigation of the sequential and medium range NOEs as a preliminary step in determining the three-dimensional structure of this protein by means of distance geometry calculations. The typical NOEs of d alpha beta(i,i + 3) and d alpha N(i,i + 3), as well as the successive strong NOEs of dNN connectivities and slowly exchanging amide protons confirmed the presence of three helical segments corresponding to the sequence regions, Ala8-Cys18, Gly42-Cys48, and Leu54-Cys61, and the existence of a beta-turn in the Gly19-Gly22 region. Our results definitely indicate that the secondary structure of human IGF-I in solution is consistent with that of insulin in the crystalline state.
authors.affiliation: Research Laboratory, Fujisawa Pharmaceutical Co., Ltd., Osaka.
authors.forename: A
authors.initials: A
authors.lastname: Sato
authors.forename: S
authors.initials: S
authors.lastname: Nishimura
authors.forename: T
authors.initials: T
authors.lastname: Ohkubo
authors.forename: Y
authors.initials: Y
authors.lastname: Kyogoku
authors.forename: S
authors.initials: S
authors.lastname: Koyama
authors.forename: M
authors.initials: M
authors.lastname: Kobayashi
authors.forename: T
authors.initials: T
authors.lastname: Yasuda
authors.forename: Y
authors.initials: Y
authors.lastname: Kobayashi
mesh_terms: D000595:Amino Acid Sequence; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011522:Protons; D013113:Spin Labels
chemical_list: D011522:Protons; D013113:Spin Labels; D007334:Insulin-Like Growth Factor I