Conformational studies of tachykinin peptides using NMR spectroscopy

Conformational analysis of two tachykinin family peptides: Scyliorhinin I (ScyI) and Scyliorhinin II (ScyII) was carried out by 1D- and 2D-NMR (DQF-COSY, TOCSY, HMQC, HMBC, NOESY and ROESY) and molecular dynamics calculation methods in water and DMSO. Scyliorhinin I is an equipotent agonist of NK-1 and NK-2 tachykinin receptors and Scyliorhinin II is a selective agonist of the NK-3 tachykinin receptor. In DMSO, two groups of conformations (major and minor) were obtained for both peptides based on the experimental data. The conformations proposed for ScyI represent a folded structure, which show certain similarities to the structures reported for other NK-1 and NK-2 tachykinin agonists. In water ScyII displays a flexible, extended structure, whereas in DMSO the structure is more compact and in the fragment from the centre to the C-terminus several beta -turns may be present.