Table 2.

FRET parameters of M-TTR adopting different conformational states

Conformational state	R (Å)	E	R 0 (Å)	Q D	n	J(λ) (nm4 M−1 cm−1)	κ 2
Folded (0 M urea)	21.3 (±1.6)	0.72 (±0.02)	24.9 (±1.4)	0.050 (±0.008)	1.332 (±0.001)	1.96 × 1014 (±0.20 × 1014)	0.87 (±0.2)
Unfolded (6 M urea)	30.8 (±1.7)	0.29 (±0.01)	26.5 (±1.4)	0.070 (±0.004)	1.384 (±0.002)	3.09 × 1014 (±0.15 × 1014)	0.67 (±0.2)
Equilibrium partially folded (1 M urea)	24.0 (±1.6)	0.63 (±0.02)	26.2 (±1.3)	0.054 (±0.003)	1.358 (±0.001)	2.66 × 1014 (±0.13 × 1014)	0.87 (±0.2)
Amyloidogenic partially folded (0 M urea, pH 4.5)	21.1 (±1.2)	0.73 (±0.02)	24.9 (±1.4)	0.049 (±0.003)	1.332 (±0.001)	2.03 × 1014 (±0.10 × 1014)	0.87 (±0.2)

E values were determined experimentally from the fluorescence spectra of DACM-M-TTR and M-TTR, respectively. Q _D was determined experimentally using free tryptophan as a reference. n was determined experimentally using a 2WAJ ABBE bench refractometer from Optika Microscopes (Bergamo, Italy). J(λ) was determined experimentally as the integral expressing the degree of spectral overlap between donor emission and acceptor absorption [44, 45]. κ ² was assumed to be 0.87 ± 0.2 for folded proteins [46] and 2/3 (0.67 ± 0.2) for unfolded proteins [44]. R ₀ values were determined using Eq. 3. R values were determined from E and R ₀ values using Eq. 4