MONO-DIMENSIONAL AND TWO-DIMENSIONAL 500-MHZ CHARACTERIZATION OF SYNTHETIC BOMBESIN AND RELATED PEPTIDES IN DMSO AND DMSO WATER

The proton nmr characterization of bombesin (BBS) and of two peptide fragments corresponding to the (1–6) and (6–14) sequences has been carried out at 500 MHz in dimethyl sulfoxide (DMSO-d6) using two-dimensional (2D) homo and 1H-13C heterocorrelated techniques. All resonances in the nmr spectra have been assigned and several coupling constants have been measured. The backbone JCHNH coupling constants are quite similar and around 7.8–8.2 Hz, pointing to an unfolded structure in DMSO-d6. The possibility of secondary structures in highly viscous mixtures of DMSO-d6–water was investigated. The existence of sequential nuclear Overhauser enhancement (NOE) effects in the C-terminal nonapeptide section may indicate a preferential site for secondary structuring.