Fig. 1.

Kinetics of the formation of amyloid fibrils monitored by thioflavin T (ThT) fluorescence. ThT exhibits enhanced fluorescence at 485 nm only when it is excited at 445 nm after binding specifically to the amyloid fibrils. In the absence of seeds, the kinetics of amyloid fibril formation shows a sigmoidal curve (solid line). The initial lag phase represents nucleation of amyloid fibrils, and the following growth phase represents an elongation of amyloid fibrils. In the presence of seeds, amyloid fibrils rapidly form by seeding without a lag phase (dashed line), indicating that nucleation is a rate-limiting step in amyloid fibrillation