3 10 helix formation in protected tripeptide

The conformational analysis of a synthetic peptide Boc-Lys(Z)-Gly-Val-NHMe has been carried out, as a model for nucleating segment in helix formation. 1 H NMR studies (270 MHz) suggested that the Gly (2) NH, Val (3) NH and NHMe groups are solvent shielded. Conformational energy calculations and intramolecular hydrogen bonding constrains favour 3 10 helix structure for the peptide. Theoretical and spectroscopic results are consistent with the presence of a transannular 4 -> 1 hydrogen bond between Lys (1) CO and NHMe with Gly (2) NH and Val (3) being sterically shielded from the solvent environment.