Structural transitions in model beta-sheet tapes

We present a molecular-scale simulation study of the structural transitions between helicoidal, helical, and tubular geometries in supramolecular beta-sheet tapes. Such geometries have been observed in different self-assembled amyloid systems (based on either natural or synthetic peptides) for which the beta-sheet tapes represent the simplest fibrillar aggregates. A coarse-grained model for the beta-sheet tapes is proposed, with chiral degrees of freedom and asymmetrical chemical properties, which provides a quantitative characterization of the structural transitions. A quantitative connection is established between the molecular properties and the elastic parameters of the supramolecular tapes.