De Novo Left-Handed Synthetic Peptidomimetic Foldamers.

The development of peptidomimetic helical foldamers with a wide repertoire of functions is of significant interest. Herein, we report the X-ray crystal structures of a series of homogeneous l-sulfono-γ-AA foldamers and elucidate their folding conformation at the atomic level. Single-crystal X-ray crystallography revealed that this class of oligomers fold into unprecedented dragon-boat-shaped and unexpected left-handed helices, which are stabilized by the 14-hydrogen-bonding pattern present in all sequences. These l-sulfono-γ-AApeptides have a helical pitch of 5.1 Å and exactly four side chains per turn, and the side chains lie perfectly on top of each other along the helical axis. 2D NMR spectroscopy, computational simulations, and CD studies support the folding conformation in solution. Our results provide a structural basis at the atomic level for the design of novel biomimetics with a precise arrangement of functional groups in three dimensions.