Fig. 5.

Riboflavin-sensitized oxidation of TTR leads to unique dbAF and dityrosine spectra and indicates riboflavin binding to TTR Samples of TTR (5.2 μM) in HEPES buffer were supplemented with 30 mM riboflavin and/or 200 mM CaCl₂ (final concentrations) as indicated. Samples were irradiated at 23 °C for 30 min using an excitation wavelength of 445 nm and slits of 2.0 nm. All samples were then applied to G-25 spin columns and centrifuged. Fluorescence emission spectra were recorded with excitation at 360 nm (A), 275 nm (B) and 315 nm (C) immediately (upper panels) and after incubation overnight at 60 °C (lower panels). The samples that were subjected to irradiation are marked with asterisks. The rectangle indicates the fluorescence spectrum of riboflavin.