β-Sheet mediated self-assembly of dipeptides of ω-amino acids and remarkable fibrillation in the solid state

Abstract

Single crystal X-ray diffraction studies show that the extended structure of dipeptide I Boc–β-Ala–m-ABA–OMe (m-ABA: meta-aminobenzoic acid) self-assembles in the solid state by intermolecular hydrogen bonding to create an infinite parallel β-sheet structure. In dipeptide II Boc–γ-Abu–m-ABA–OMe (γ-Abu: γ-aminobutyric acid), two such parallel β-sheets are further cross-linked by intermolecular hydrogen bonding through m-aminobenzoic acid moieties. SEM (scanning electron microscopy) studies reveal that both the peptides I and II form amyloid-like fibrils in the solid state. The fibrils are also found to be stained readily by Congo red, a characteristic feature of the amyloid fiber whose accumulation causes several fatal diseases such as Alzheimer's, prion-protein etc.