Tetrameric β³-Peptide Bundles

A question of identity: There is significant interest in the design of discrete, nonproteinaceous quaternary structures. We recently described a series of β3‐peptides that assemble into stable octameric bundles. Here we show that bundle stoichiometry is controlled by the bundle core side‐chain identity, whereby mutation of leucine to valine supports formation of discrete and stable tetrameric bundles.