Figure 1

Formation of dityrosine crosslinks in A β 42 fibrils. Preformed Aβ42 fibrils (20 μM) were incubated in the presence of Cu²⁺/H₂O₂ for 72 hours and the appearance of dityrosine detected using fluorescence (a). b) The dityrosine content was confirmed using LC-ESIMS/MS and this shown with relative abundance on y-axis. i) LC-ESIMS/MS from authentic synthetic dityrosine, ii) hydrolysate from oxidized preformed Aβ42 fibrils, iii) hydrolysate from Aβ42 fibrils formed under oxidation conditions for three days (the fibrils were obtained from incubation of soluble Aβ42 with Cu²⁺/H₂O₂ in water at 37°C and agitation) (c, d) Electron micrographs showing the morphology of fibrils prior to oxidation (c) and following 24 hour oxidation (d) (diameters approximately 100–150 Å).