Fig. 4.

Structural/oxidative changes in TTR are reflected in dbAF spectra Samples of TTR with a C-terminal histidine tag (4.4 μM) in 30 mM Tris, 60 mM NaCl, pH 7.3 were subjected to a thermal cycle of denaturation (from 20 °C to 80 °C) and renaturation (from 80 °C to 20 °C) in the absence or presence of 200 mM CaCl₂. Next, each sample was divided into two portions, and one half of each sample was supplemented with 1 mM DTT. All samples were incubated at room temperature, and the fluorescence emission spectra were recorded with excitation at 360 nm after 2 and 4 days of incubation (A). After the third day of incubation, the fresh portion of DTT (1 mM final concentration) was added to the sample that was previously supplemented with DTT. (B) shows the excitation spectra collected at 438 nm and 455 nm for the samples with corresponding emission spectra shown in (A).