Fig. 1: Heme arrests fibrillation of α-Syn by converting the heterogeneous mass of aggregates into uniform-sized oligomers.

a Dose-dependent study (ThT fluorescence) of 200 μM monomeric α-Syn preincubated for 96 h with heme. b, c Negative-stain TEM and AFM micrographs of b α-Syn fibrillar network formed in the absence of heme after 96 h of aggregation; c α-Syn oligomers₁ (white squares, TEM) formed after 96 h incubation with heme under aggregation-inducing conditions (preincubation). d Comparison of the seeding effect of heme-treated seeds (in blue) and untreated seeds (in red) on monomeric α-Syn; the sigmoidal aggregation kinetics profile of 200 μM α-Syn, without any seeds added (in black) has been added for comparison. e Dose-dependent study (ThT fluorescence) of the disaggregation of 96 h fibrils upon addition of heme (postincubation). f negative-stain TEM (white squares) and AFM micrographs depict formation of oligomers₂ upon disaggregation by heme of 96 h fibrils. Error bars in ThT experiments represent ±SEM and have been calculated from eight independent experiments. The scale bars in the AFM micrographs represent 100 nm. The height distribution histograms are presented beneath their corresponding AFM image. The ratio of α-Syn/heme was maintained at 25:1 for all of the above studies.