Table 1. Fitting to three-state model of equilibrium denaturation curves of the WT scFV-h3D6 and its variants. Fitting to the two-state model has been done for 0–5.5 M Urea and for 5–9.2 M Urea, to be compared with the three-state model.

	First transition			Second transition
Parameter	ΔGΙ-N	mI-N	[D]I-N	ΔGU-I	mU-I	[D]U-I
Variant, states
WT, three-state	19.3 ± 0.7	7.0 ± 0.3	2.76	36.9 ± 5.7	5.2 ± 0.8	7.10
, two indep. two-state	19.7 ± 0.7	7.1 ± 0.3	2.78	32.0 ± 4.2	4.5 ± 0.6	7.11
C1, three-state	21.0 ± 0.9	7.1 ± 0.3	2.96	31.1 ± 6.4	4.5 ± 0.9	6.91
, two indep. two-state	21.1 ± 1.0	7.2 ± 0.4	2.93	35.7 ± 3.7	5.1 ± 0.5	7.00
C2, three-state	22.3 ± 0.7	6.9 ± 0.2	3.23	36.2 ± 5.8	5.1 ± 0.8	7.10
, two indep. two-state	22.5 ± 0.8	7.0 ± 0.3	3.21	37.7 ± 3.6	5.3 ± 0.5	7.11
C3, three-state	24.4 ± 0.5	7.7 ± 0.2	3.17	38.6 ± 3.9	5.3 ± 0.6	7.28
, two indep. two-state	24.6 ± 0.5	7.8 ± 0.2	3.15	36.5 ± 4.8	5.0 ± 0.6	7.30

ΔG in KJ mol⁻¹; m in KJ mol⁻¹ M⁻¹. n = native state; I = intermediate state; U = unfolded state; [D] between states = denaturant 50% in M.