1H-NMR assignment and secondary structure of human insulin-like growth factor-I (IGF-I) in solution.
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Sato A, Nishimura S, Ohkubo T, Kyogoku Y, Koyama S, Kobayashi M, Yasuda T, Kobayashi Y
1H-NMR assignment and secondary structure of human insulin-like growth factor-I (IGF-I) in solution.
J Biochem. 1992 Apr;111(4):529-36.
- PubMed ID
- 1319992 [ View in PubMed]
- 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.