Figure 4.

Photooxygenation of Aβ amyloid using LEV (2). A) Reaction time course. A PB solution (pH 7.4) containing aggregated Aβ_1–42 (20 × 10⁻⁶ m) and 2 or 3 (1 × 10⁻⁶ m, 5 mol%) was photoirradiated (λ = 595 nm, 10 mW) at 37 °C, and the reaction progress was analyzed using MALDI‐TOF MS (n = 3 experiments, mean ± SEM). B) Evaluation of amyloid selectivity. A PB solution (pH 7.4) containing aggregated Aβ_1–42 (agg. Aβ), AT4, LeuP, Sst, or SubP (20 × 10⁻⁶ m each) was photoirradiated (λ = 595 nm, 10 mW) in the presence of 2 (1 × 10⁻⁶ m, 5 mol%) at 37 °C for 60 min. Yield was analyzed using MALDI‐TOF MS (n = 3 experiments, mean ± SEM). C) Spectroscopic time course for the generation of 3 from 2. A PB solution (pH 7.4) containing 2 (20 × 10⁻⁶ m) with (right) or without (left) Aβ amyloid (20 × 10⁻⁶ m) was photoirradiated (λ = 595 nm, 10 mW) at 37 °C, and the absorption spectra were measured. The control is the absorption spectrum of 3. D) Conversion of 2 to 3 under photoirradiation with variable wavelength light. A PB solution (pH 7.4) containing 2 (20 × 10⁻⁶ m) was irradiated at the indicated wavelength (10 mW) at 37 °C for 30 min, and the absorption spectra were measured. The control is the absorption spectrum of 2. E) Activation of 2 to 3 through a hydrogen atom transfer (HAT) process. To a PB solution (pH 7.4) of 2 (20 × 10⁻⁶ m), 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical (20 × 10⁻⁶ m) was added and the mixture was incubated in the dark at 37 °C for 30 min under air. After incubation, the absorption spectrum of the solution was measured.