Many proteins and peptides are able to self-assemble in solution in vitro and in vivo to form amyloid-like fibrils. These fibrils share common structural characteristics. In order for a fibril to be characterized as amyloid, it is expected to fit certain criteria including the composition of cross-β. Here we describe how the formation of amyloid fibrils can be characterized in vitro using a variety of methods including circular dichroism and intrinsic tyrosine/tryptophan fluoresence to follow conformational changes; Thioflavin and/or ThS assembly to monitor nucleation and growth; transmission electron microscopy to visualize fibrillar morphology and X-ray fiber diffraction to examine cross-β structure.
Keywords: Circular dichroism; Cross-β; Electron microscopy; Oligomer; Protofibril; Protofilaments; Self-assembly; Thioflavin T/S fluorescence; Tyrosine/tryptophan fluorescence; X-ray fiber diffraction.