Figure 5

Cu²⁺ ions affect α-syn fibril growth and structure.

400 μM α-syn fibrils grown in 20 mM HEPES buffer, pH 7.4 with and without Cu²⁺ with agitation of 450 rpm. (a) ThT fluorescence assay over 120 hours revealed increased fluorescence for α-syn incubated with Cu²⁺ compared to α-syn without Cu²⁺. (b) Shows fluorescence at 405 nm following incubation of α-syn for 120 hours confirming that dityrosine forms in 400 μM α-syn and that Cu²⁺ enhances its formation. (c) TEM micrographs reveal no significant morphological changes between α-syn with or without Cu²⁺, although there appear to be increased number of fibrils in Cu²⁺ induced samples, consistent with the ThT results. (d) X-ray fibre diffraction patterns collected from partially aligned α-syn fibrils incubated at 400 μM α-syn without and with Cu²⁺ reveals the characteristic cross-β pattern. Inset shows a zoom of ~35 Å reflection close to the back stop.