Structural study on silkworm eclosion hormone fragment (1-34) in solution by proton nuclear magnetic resonance...

Eclosion hormone (EH) is a neuropeptide hormone which controls the ecdysis behavior in insect. The three dimensional structure of the N-terminal fragment (1-34) of the eclosion hormone which was predicted to contain a compact region crucial for the EH activity was studied in 50% d3-trifluoroethanol(TFE)/50% H2O at pH 3 and 298 K by 1H NMR spectroscopy with the combined use of distance geometry and molecular dynamics calculations. NMR results indicated that the fragment actually assumes an alpha-helix between Ala10 and Gln20, but no rigid structure is present from Cys21 through the C-terminus and for the N-terminal region (Ser1-Asp9). The elucidated structure was compared with the predicted structure of the native EH for the further development of the design of the insecticide.