3<inf>10</inf> 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. 1H 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 310 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.