Ordered self-assembly of a glycine-rich linear and cyclic hexapeptide: contrasting ultrastructural morphologies of fiber growth

Abstract

Self-assembly is a widely occurring phenomenon in chemistry and biology, where nanoscopic building blocks are organized to yield well-defined aggregates and supramolecular structures. One such example is ordered protein aggregation, which is primarily driven by hydrogen bonding, hydrophobic interactions and other non-covalent stabilizing factors. This report describes differing ultrastructural morphologies of a cyclic and linear hexapeptide, possessing the same amino acid sequence. Microscopic studies reveal two dissimilar pathways leading to self-assembly: one with spherical pre-fibrillar intermediate, while another one displaying spherulite-like "Maltese-cross" patterns. Detailed analysis provides crucial insight into initiation, propagation and growth of peptide fibers in two constructs.