Cyclo(-Gly-DSIP), a cyclic analog of the delta-sleep-inducing peptide: Computer simulation of spatial structure involving NMR data

The spatial structure of cyclo(-Gly-DSIP-), a physiologically active analog of the delta sleep-inducing peptide, was determined by computer modelling using H-1 NMR data. An interesting feature of the spatial structure in DMSO was detected. One side of almost planar resulting conformation is formed by the side chains of the Asp(5), Ser(7) and Glu(9) residues, the side chain of the Trp(1) residue forming the other part of the outer surface; This feature may be associated with the functional properties of the peptide.