Cooperative Effect of the Two Hydrogen Bonding Types on 11/9‐Helical Folding of α/β‐Peptides

[摘要] α/β‐Peptide 11/9‐helix is an unconventional helical structure in which 11‐ and 9‐membered ring hydrogen bonds alternate along the helical axis. We have examined the interplay and the relative strength of these two hydrogen bonding types by IR, NMR, and X‐ray crystallographic methods. A pair of two adjacent hydrogen bonds with opposite directionality cooperatively stabilized each other in non‐hydrogen‐bonding solvents. In contrast, an unpaired hydrogen bond was unstable to promote helical folding. The IR and the NMR data of α/β‐depsipeptides suggested that a 9‐membered ring hydrogen bond is favored over an 11‐membered ring hydrogen bond.

[学科分类] 化学（综合）

[关键词] α/β‐peptide;Helix;Hydrogen bonding;Crystal structure