Solid‐State NMR Spectroscopic Investigation of Aβ Protofibrils: Implication of a β‐Sheet Remodeling upon Maturation into Terminal Amyloid Fibrils

The secondary structure elements in Aβ protofibrils (see TEM image) were determined at a single residue level by solid-state NMR spectroscopy. The β-sheet elements of the mature fibrils are already preformed in protofibrils, but these regions have to elongate during the conversion into mature fibrils. The data have important implications for understanding the process of fibril formation in general as well as the structural basis of Alzheimer's disease.