Hairpin Folding Behavior of Mixed α/β-Peptides in Aqueous Solution

The invention of new strategies for the design of protein-mimetic oligomers that manifest the folding encoded in natural amino acid sequences is a significant challenge. In contrast to the a-helix, mimicry of protein beta-sheets is less understood. We report here the aqueous folding behavior of a prototype alpha-peptide hairpin model sequence varied at cross-strand positions by incorporation of 16 different beta-amino acid monomers. Our results provide a folding propensity scale for beta-residues in a protein beta-sheet context as well as high-resolution structures of several mixed-backbone alpha/beta-peptide hairpins in water.