Table 2.

Thermodynamic parameters for pp32 L60A unfolding by pressure and urea

		NMR observable
Perturbation/unfolding model		Unfolded state methyl peak ∼0.92 ppm	Unfolded state methyl peak ∼0.85 ppm	Folded state backbone –NH <all residues>	Trp155 indole NH unfolded state peak	CD*
L60A pressure/two-state peaks	ΔG	−1.7 ± 0.2	−1.7 ± 0.3	−2.0 ± 0.4	−1.8 ± 0.1	—
	ΔV	88 ± 9	92 ± 12	138 ± 22	63 ± 3	—
L60A pressure/three-state NI†	ΔG	—	—	−2.0 ± 0.4		—
	ΔV	—	—	126 ± 18		—
L60A pressure/three-state IU†	ΔG	—	—	−0.6 ± 0.4		—
	ΔV	—	—	24 ± 11		—
L60A urea/two-state peaks	ΔG	−3.8 ± 0.4	−4.0 ± 0.6	−2.6 ± 0.5	−3.6 ± 0.2	−4.1 ± 0.1
	m value	2.4 ± 0.3	2.5 ± 0.4	2.0 ± 0.3	2.3 ± 0.1	2.61 ± 0.01*

ΔG and ΔV values are in kilocalories⋅mole⁻¹ and milliliter⁻¹. m values are in kilocalorie⁻¹⋅mole⁻¹⋅molar⁻¹. Individual values are the fitted value ± SE of the least-squares fit. Backbone NH are the mean ± SD over all residues. Fluorescence results are the average of least-square fits of three independent experiments ± SEM.

^*Dao et al. (21).

^†Only residues showing intermediate peaks were fit to three-state transition. Intensity profiles from all other residues were fit to a two-state model.