Fig. 1.

Schematic representation of sm-FRET experiment to probe the aggregation of alpha-synuclein (αS). (A) A 1:1 stoichiometric ratio of αS monomer labeled with Alexa Fluor 488 and Alexa Fluor 594, shown as blue and orange spheres, was combined at a given initial concentration and allowed to aggregate. During the process, the monomeric protein assembles into oligomers, the main focus of the present experiments, and then amyloid fibrils. Aliquots were withdrawn, diluted, and analyzed using a single-molecule microscope. (B) Schematic of the setup used for the single-molecule FRET experiments.