FIGURE 1.

Comparison of the aggregation, redox cycling, and dityrosine formation capacities of Aβ peptides. A, Aβ (5 μm) fibrillization kinetics measured by thioflavin-T assay (data cropped at start of plateau due to signal decay as Aβ sediments in microplate wells). B, kinetics of ^•OH formation in reactions of Aβ (20 μm) with CuCl₂ (20 μm) and ascorbate (300 μm) as measured by 3-CCA fluorescence assay. Kinetics of dityrosine formation in reactions of Aβ (10 μm) with CuCl₂ (10 μm) and ascorbate (100 μm) Aβ(1–40) and Aβ3pE-40 peptides (C), Aβ(1–42) and Aβ3pE-42 peptides (D), measured by fluorescence spectrometry of dityrosine bond (320 nm excitation and 420 nm emission). E, relationship between Aβ hydrophobicity and dityrosine formation rate. F, relative efficiency of Aβ-dityrosine formation was further calculated as a ratio of the amount of dityrosine formed per unit of ^•OH produced, plotted against Aβ hydrophobicity. All measurements were repeated a minimum of three times over separate days using freshly prepared Aβ solutions. Data shown are mean ± S.E.