Table 1.

Thermodynamic parameters for WT pp32, I7A, and L139A unfolding by pressure and urea

			NMR observable
Variant/perturbation	Parameter		U CH3 peak ∼0.92 ppm	U CH3 peak ∼0.85 ppm	Backbone –NH <all residues>		F and U Trp155 indole NH	Fluorescence	CD*
WT pressure† (1.4 M urea)	ΔG		−4.6 ± 0.4 (8.6 0 M U)	−5.4 ± 0.5 (9.4 0 M U)	−3.2 ± 0.4 (7.2 at 0 M U)		−3.4 ± 1.6 (7.4 at 0 M U)	−3.6 ± 0.1 (7.6 at 0 M U)	—
	ΔV		170 ± 15	166 ± 14	110 ± 12†		109 ± 18	111 ± 7	—
WT urea	ΔG		ND	ND	−6.2 ± 1.1		−7.5 ± 0.5	−7.9*	7.9 ± 0.2*
	m value		ND	ND	2.3 ± 0.4		2.7 ± 0.2	2.86*	2.86 ± 0.02*
I7A pressure	ΔG		−4.2 ± 0.1	−3.2 ± 0.1	−2.4 ± 0.3		−3.7 ± 0.6	−3.4 ± 0.1 4.25 at 0M U‡	—
	N-R4	R5-C-cap			2.0 ± 0.4	3.2 ± 0.2
	ΔV		88 ± 8	67 ± 3	63 ± 8		64 ± 17	75 ± 3‡	—
	N-R4	R5-C-cap			59 ± 10	71 ± 4
I7A urea	ΔG		−6.2 ± 0.3	−6.6 ± 0.5	−3.7 ± 2.3		−6.0 ± 0.4	—	−5.86 ± 0.06*
					−2.8 ± 1.5	−5.7 ± 2.7
	m		2.9 ± 0.2	3.0 ± 0.4	2.1 ± 1.0		2.9 ± 0.2	—	2.85 ± 0.04*
					1.7 ± 0.7	2.9 ± 1.3
L139A pressure (0 M urea)	ΔG		−4.6 ± 0.2	−4.0 ± 0.2	−4.5 ± 0.6		−4.7 ± 0.3	−4.0 ± 0.2
	ΔV		180 ± 8	162 ± 8	178 ± 13		180 ± 11	153 ± 6	—
L139A urea	ΔG		—	—	—		—	—	4.4 ± 0.2*
	m value		—	—	—		—	—	3.4 ± 0.1*

ΔG and ΔV values are in kilocalories⋅mole⁻¹ and milliliter⁻¹. m values are in kilocalorie⁻¹⋅mole⁻¹⋅molar⁻¹. CD, circular dichroism. Individual values are the fitted value ± SE of the least-squares fit. Backbone NH are the mean ± SD over all residues. The Trp NH F and U peaks were fit globally assuming equal intensities for the unfolded and folded state peaks. Fluorescence is the average of least-square fits of three experiments ± SEM.

^*Dao et al. (21).

^†Fossat et al. (22).

^‡Data were acquired in 0.3 M urea.