β-Peptide bundles: Design. Build. Analyze. Biosynthesize

Peptides containing beta-amino acids are unique non-natural polymers known to assemble into protein-like tertiary and quaternary structures. When composed solely of beta-amino acids, the structures formed, defined assemblies of 14-helices called beta-peptide bundles, fold cooperatively in water solvent into unique and discrete quaternary assemblies that are highly thermostable, bind complex substrates and metal ion cofactors, and, in certain cases, catalyze chemical reactions. In this Perspective, we recount the design and elaboration of beta-peptide bundles and provide an outlook on recent, unexpected discoveries that could influence research on beta-peptides and beta-peptide bundles (and beta-amino acid-containing proteins) for decades to come.