Oligomers of α-ABpeptoid/β -peptide hybrid.

Peptoids, oligomers of N-substituted glycines, have been attracting increasing interest due to their advantageous properties as peptidomimetics. However, due to the lack of chiral centers and amide hydrogen atoms, peptoids, in general, do not form folding structures except that they have α-chiral side chains. We have recently developed "peptoids with backbone chirality" as a new class of peptoid foldamers called α-ABpeptoids and demonstrated that they could have folding conformations owing to the methyl groups on chiral α-carbons in the backbone structure. Here we report α-ABpeptoid/β -peptide oligomers as a unique peptidomimetic structure with a heterogeneous backbone. This hybrid structure contains a mixed α-ABpeptoid and β -peptide residues arranged in an alternate manner. These α-ABpeptoid/β -peptide oligomers could form intramolecular hydrogen bonding and have better cell permeability relative to pure peptide sequences. These oligomers were shown to adopt ordered folding structures based on circular dichroism studies. Overall, α-ABpeptoid/β -peptide oligomers may represent a novel class of peptidomimetic foldamers and will find a wide range of applications in biomedical and material sciences.