Effects of Alternative Side Chain Pairings and Reverse Turn Sequences on Antiparallel Sheet Structure in β-Peptide Hairpins

We describe a series of β-peptide hexamers that allow us to explore relationships between sequence and hairpin folding. Different reverse turn segments are compared at the central two positions, and the outer residues allow a variety of interstrand side chain−side chain pairings. NMR analysis in methanol demonstrates that several reverse turn and side chain pairing arrangements are compatible with antiparallel β-peptide sheet structure; however, none of the β-peptides folds in water.