Figure 2.

Subunit exchange is a robust measure of TTR tetramer kinetic stability at various ratios of tagged to untagged tetramer concentrations. (A) After incubation in standard phosphate buffer for 8 days, different ratios of the starting concentrations of WT and FT₂·WT TTR yield different ratios of the five tetramer peaks. (B) The kinetics of subunit exchange, as measured by fraction exchange of peak 3, were followed over a time course of 8 days for the indicated ratios of WT to FT₂·WT TTR. Symbols represent means; error bars represent the SEM, and lines represent fitted curves. (C) The time course of appearance or disappearance of the five tetramer peaks in absolute terms varies according to the molar ratio of the initial populations of WT and FT₂·WT TTR (top panels). However, the time course of the increase in fraction exchange calculated for each peak is very similar (bottom panels): (left) 5 μM WT TTR and 5 μM FT₂·WT TTR, (middle) 5 μM WT TTR and 2 μM FT₂·WT TTR, and (right) 5 μM WT TTR and 1 μM FT₂·WT TTR. Symbols represent means; error bars represent the SEM, and lines represent fitted curves.