Bottom-up design of peptide shapes in water using oligomers of N-methyl-l/d-alanine

De novo design of peptide shapes is of great interest in biomolecular science since the local peptide shapes formed by a short peptide chain in the proteins are often key to biological activities. Here, we show that the de novo design of peptide shapes with sub-nanometer conformational control can be realized using peptides consisting of N-methyl-l-alanine and N-methyl-d-alanine residues. The conformation of N-methyl-l/d-alanine residue is largely fixed because of the restricted bond rotation and hence can serve as a scaffold on which we can build a peptide into a designed shape. The local shape control by per-residue conformational restriction by torsional strains starkly contrasts with the global shape stabilization of proteins based on many remote interactions. The oligomers allow the bottom-up design of diverse peptide shapes with a small number of amino acid residues and would offer unique opportunities to realize the de novo design of biofunctional molecules.