Fig. 3.

Transformations and anodic peak potentials (E_pa) of L1, L2, and L3. (A) Optical changes of L1 upon addition of Cu(II) with and without Aβ₄₀ under aerobic conditions. The new appearance of the peaks is indicated with black arrows. Conditions were as follows: [Aβ₄₀], 25 μM; [CuCl₂], 25 μM; [compound], 50 μM; room temperature; incubation for 1 h (black), 4 h (red), and 12 h (blue). (B) Structural variations of L1 in the presence of Cu(II)-treated Aβ₄₀, monitored by ESI–MS. Conditions were as follows: [Aβ₄₀], 100 μM; [CuCl₂], 100 μM; [L1], 500 μM; incubation for 1 h; 20 mM ammonium acetate, pH 7.2; 37 °C; no agitation. The sample was diluted with H₂O by 10-fold prior to injection to the mass spectrometer. (C) Cyclic voltammograms of L1, L2, and L3 in DMSO at the scan rate of 250 mV/s. The E_pa values of the compounds at various scan rates are summarized in SI Appendix, Table S2. Conditions were as follows: [compound], 1 mM; 0.1 M tetra-N-butylammonium perchlorate; room temperature; three electrodes composed of the glassy carbon working electrode, platinum counter electrode, and Ag/Ag(I) reference electrode.