Several neurodegenerative disorders in humans are associated with the conversion of peptides and proteins from their soluble functional forms into well-defined fibrillar aggregates,generally described as amyloid fibrils.Many other proteins,not related to protein deposition diseases,have been found to form amyloid-like fibrils in vitro,suggesting that the ability to form the amyloid structure is encoded in the backbone interactions of a generic polypeptide chain.Notably,amyloids are produced by some organisms for functional properties without deleterious effects.The emergence of a limited menu of native-like conformations for a single chain and of beta-aggregate structures for multiple chains was rationalized theoretically within a sequence independent coarse-grained framework.