The solution conformation of the luteinizing hormone-releasing hormone (LHRH) anti-sense and reversed anti-sense peptides

The LHRH anti-sense peptide (Ser1-Arg2-Ala3-Gln4-Ser5-Ile6-Gly7-Pro8-Val9-Leu10) and the inversed sequence, the LHRH inversed anti-sense peptide, have been studied by 1H and 13C NMR in one and two dimensions. The spectroscopic evidence, obtained in CD3OH/H2O (60/40) solution at pH 3.6, indicates that the first four amino acids of the anti-sense peptide form one complete 310-helical turn followed by an extended conformation for the rest of the peptide. On the time-averaged NMR scale the molecules in the 310-helical conformation are in fast exchange with the molecules that are extended throughout (major conformer). The reversed anti-sense peptide exhibits less discernible features. It appears likely that a small percentage of the molecules form a β-turn in the C-terminal four residues. Another β-turn might be located in the Val2-Ile5 fragment. Both turns occur in very minor concentrations only, and therefore it is impossible to define what kind of β-turns are present. Keywords: LHRH anti-sense, inversed anti-sense, conformation, NMR.