Non-classical Helices with cis Carbon-Carbon Double Bonds in the Backbone: Structural Features of alpha, gamma-Hybrid Peptide Foldamers

摘要

The impact of geometrically constrained cis alpha, beta-unsaturated gamma-amino acids on the folding of alpha, gamma-hybrid peptides was investigated. Structure analysis in single crystals and in solution revealed that the cis carbon-carbon double bonds can be accommodated into the 12-helix without deviation from the overall helical conformation. The helical structures are stabilized by 4 -> 1 hydrogen bonding in a similar manner to the 12-helices of beta-peptides and the 3(10) helices of alpha-peptides. These results show that functional cis carbon-carbon double bonds can be accommodated into the backbone of helical peptides.