Local versus Global Control of Helical Folding in β-Peptide Segments Using Hydrazino Turns.

Rational control of the self-organization of β-peptides sequences to adopt regular secondary structures is an important challenge in peptidomimetic foldamer science. By replacing the N - and C -terminal residues of homooligomers of trans -2-aminocyclobutanecarboxylic acid ( t ACBC) _n with N -aminoazetidine-2-carboxylic acid, an 8-helical topology is shown to dominate for sequences up to n = 7. This constitutes an atomic-level tool to override locally the preferred global 12-helix secondary structure of the corresponding t ACBC homooligomers of the same length.