Fig. 2: Fluorescence assays and structural analysis of HttEx1 aggregation in presence and absence of curcumin.

a Q32-HttEx1 (61 µM) aggregation was monitored by ThT assays, measuring fluorescence in the presence and absence of curcumin (molar ratio indicated). b Q44-HttEx1 (67.5 µM) aggregation by ThT fluorescence in the presence and absence of curcumin. The curves indicate the mean of the triplicate values and the figure with the error bars is plotted in Supplementary Fig. 2a, b. c–f Negative stain TEM micrographs of 61 µm Q32-HttEx1 fibrils, formed c without curcumin; d with 8.5 µM curcumin; e with 12 µM curcumin; f with 20 µM curcumin. Black scale bars indicate 100 nm, and white bars show 50 nm. Micrographs shown in c, d, e and f are representative data from a total of 58, 41, 32 and 36 images obtained, respectively. g–j TEM-based fibril core width histograms corresponding to samples in c–f. The vertical dashed line marks the average width of fibrils formed in absence of curcumin. The yellow lines perpendicular to the fibril axis mark locations of fibril width measurements. k,l TEM micrographs of 50 µM Q44-HttEx1 fibrils k formed in absence and l in presence of 16.6 µM of curcumin at room temperature. Micrographs shown in k and l are representative data from a total of 28 and 45 images obtained, respectively. m Fibril width analysis of Q44-HttEx1 fibrils prepared without curcumin and in presence of curcumin. n SAXS profile and o size distribution profile for Q32-HttEx1 fibrils prepared in presence and absence of curcumin. Dashed and solid black lines show fits of the data with models of either isolated or bundled fibrils (see text).