The imide-dipeptides that show strong and stable β-sheet-like interactions compared with natural sequence

In this Letter, we report solution behavior of two imide-dipeptides containing l-alanine and l-leucine residues. In contrast to natural sequence, the imide-dipeptidyl backbone contains distinct features: self-pairing H-bonds, topochemical symmetry, a peptide polindron sequence, and different orientations of side chains. The solution behavior in chloroform reveals that both the imide-dipeptides adopt β-folding conformations and form β-sheet-like assembly. Most surprisingly, they form more stable and stronger H-bonds than the natural counterpart, and thus show different H-bonding patterns from the natural sequence.