Depsipeptide analogues of elastin repeating sequences: synthesis

Depsipeptide analogues of peptide sequences can help in elucidating the role of specific hydrogen bonds in determining the conformation in peptides. The repeating pentapeptide and hexapeptide sequences of elastin have been suggested to contain a type II beta-turn with a 4----1 hydrogen bond. Depsipeptide analogues of the repeating sequences of elastin in which this 4----1 hydrogen bond cannot exist were synthesized. A fragment condensation approach was employed in which the depsipeptide ester bond was introduced early in the synthesis. This approach proved to be effective, although the increased lability of the depsipeptide ester bond resulted in side products and low yields in some reactions.