Helix conformation of a small peptide melittin in a methanol-water mixed solvent studied by NMR

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Temperature dependence of the α-helix conformation of bee venom melittin in methanol-water mixed solvents has been examined by NMR, in order to elucidate conformation stability and a phase diagram. At high methanol concentration of 100 - ca. 80 wt.%, melittin forms a full α-helix conformation in the temperature range from 25 °C to 60 °C. At intermediate methanol concentration of ca. 80 - ca. 25 wt.%, it undergoes a thermal transformation from a full α-helix to a partial α-helix. In solutions of low methanol concentrations of ca. 25 - 0 wt.%, partial α-helix monomers and their selfaggregated conformers coexist at low temperatures, and the relative number of the monomers increases with increase in temperature. The monomers turn to a random coil state at high temperatures only below ca. 10 wt. % methanol concentrations. The thermal transitions are discussed from the viewpoint of stability of intra-molecular hydrogen bonds and intermolecular hydrophobic interactions.

Original languageEnglish
Pages (from-to)318-326
Number of pages9
JournalProtein and Peptide Letters
Issue number3
Publication statusPublished - Mar 1 2011


All Science Journal Classification (ASJC) codes

  • Structural Biology
  • Biochemistry

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