Ultrafast infrared spectroscopy of amylin solution and fibrils

The aggregation of proteins from their native functional state to highly organized amyloid fibrils is associated with a wide range of diseases, including Alzheimer’s and Huntington’s disease and type 2 diabetes [1,2]. Despite the fact that each disease is associated with a particular protein, the amyloid fibrils have many characteristics in common. For example, they typically contain straight and unbranched fibrils, with diameters on the order of 10 nm and varying lengths ranging from 100 nm to many microns. They are rich in Β-sheet content, and peptides in the fibril usually adopt a “cross-Β" configuration, in which continuous Β-strands are arranged perpendicular to the fibril axis and are hydrogen bonded along the fibril axis [2,3]. For detection, the fibrils can be stained with Congo red and produce a characteristic green birefringence under polarized light [1,3].