COMMON CORE STRUCTURE OF AMYLOID FIBRILS BY SYNCHROTRON X-RAY-DIFFRACTION

Tissue deposition of normally soluble proteins as insoluble amyloid fi brils is associated with serious diseases including the systemic amylo idoses, maturity onset diabetes, Alzheimer's disease and transmissible spongiform encephalopathy. Although the precursor proteins in differe nt diseases do not share sequence homology or related native structure , the morphology and properties of all amyloid fibrils are remarkably similar. Using intense synchrotron sources we observed that six differ ent ex vivo amyloid fibrils and two synthetic fibril preparations all gave similar high-resolution X-ray fibre diffraction patterns, consist ent with a helical array of beta-sheets parallel to the fibre long axi s, with the strands perpen dicular to this axis. This confirms that am yloid fibrils comprise a structural superfamily and share a common pro tofilament substructure, irrespective of the nature of their precursor proteins. (C) 1997 Academic Press Limited.