Researchers generated 62 lysine-to-glutamine (K-to-Q) variants of α-synuclein to systematically probe how electrostatic interactions in the fibril core shape the protein's aggregation energy landscape across de novo nucleation, fibril elongation, and secondary nucleation. Mutations at core-forming residues dramatically reshaped aggregation, producing fibril polymorphs incompatible with wild-type elongation, while peripheral mutations only moderately slowed aggregation. Flow Induced Dispersion Analysis (FIDA), on a Fida 1 instrument, was used to quantify residual monomer concentration and assess the oligomeric state of the soluble supernatant following aggregation assays. It is an example of using FIDA to monitor protein aggregation and quantify soluble monomer and oligomer species in amyloid formation studies.