Review: structure of amyloid fibril in diseases

Tissue deposition of normally soluble proteins, or their fragments, as insoluble amyloid fibrils causes both acquired and hereditary systemic amyloidoses, which is usually fatal. Amyloid is associated with serious diseases such as Alzheimer’s disease, type 2 diabetes, Parkinson’s Disease, Huntington’s Disease, cancer and the transmissible spongiform encephalopathies. Information concerning the structure and mechanism of formation of fibrils in these diseases is critical for understanding the process of pathology of the amyloidoses and to the development of more effective therapeutic agents that target the underlying disease mechanisms. Structural models have been made using information from a wide variety of techniques, including electron microscopy, X-ray diffraction, solid state NMR, and Congo red and CD spectroscopy. Although each type of amyloidosis is characterised by a specific amyloid fibril protein, the deposits share pathognomonic histochemical properties and the structural morphology of all amyloid fibrils is very similar. In fact, the structural similarity that defines amyloid fibres exists principally at the level of β-sheet folding of the polypeptides within the protofilament, while the different types vary in the supramolecular assembly of their protofilaments.