Chirality Inversion upon Coassembly of Stereoisomeric Short Peptides with Like-Handedness

Despite numerous reports devoted to chirality inversion during the self-assembly of single chiral components, chirality inversion in the coassembly of two or more chiral components remains largely unexplored. Here we report the supramolecular chirality inversion via the coassembly of the two different stereoisomers of a minimalistic amphiphilic I3K sequence with like-handedness in their self-sorting assembly. The coassembled nanofibrils exhibit noticeable helix inversion in a wide range of mixing ratios, compared to individual peptide nanofibrils. Theoretical simulations reveal that to facilitate the interstrand H-bonding between isomeric β-strands within a mixed β-sheet, those with a homochiral backbone will undergo chirality inversion due to their structural flexibility. The inverted strands with two heterogeneous interfaces within the sheet typically display larger twisting degrees and are responsible for inducing helix inversion of the sheet and final β-sheet nanofibrils, and thus, helix inversion of the final nanofibrils can be regulated by tuning the ratio of the two components. This study lays a foundation for manipulating the suprastructure chirality of peptide bionanomaterials through coassembly.