Table 2.
Thermodynamic parameters obtained for test proteins using different denaturant titration strategies.
| Protein | NT.LabelFree |
AB2 |
||||
|---|---|---|---|---|---|---|
| mD–N (kcal·mol− 1∙ M− 1) |
[Denaturant]50% (M) |
ΔGD−N0 (kcal·mol− 1) |
mD–N (kcal·mol− 1·M− 1) |
[Denaturant]50% (M) |
ΔGD−N0 (kcal·mol− 1) |
|
| WW domaina | 0.8 ± 0.1 | 1.90 ± 0.20 | 1.6 ± 0.2 | 0.9 ± 0.1 | 1.70 ± 0.30 | 1.4 ± 0.2 |
| Cyt b562 | 1.5 ± 0.2 | 2.20 ± 0.07 | 3.2 ± 0.3 | 1.4 ± 0.1 | 2.28 ± 0.03 | 3.1 ± 0.1 |
| Lysozyme | 3.5 ± 0.5 | 4.02 ± 0.03 | 14.0 ± 2.0 | 3.4 ± 0.6 | 4.11 ± 0.04 | 14.0 ± 2.0 |
| CI2 | 2.0 ± 0.3 | 3.81 ± 0.06 | 7.7 ± 1.1 | 2.2 ± 0.2 | 3.87 ± 0.03 | 8.5 ± 0.8 |
| R16 α-spectrin | 2.2 ± 0.3 | 3.32 ± 0.04 | 7.3 ± 1.0 | 1.7 ± 0.2 | 3.35 ± 0.04 | 5.7 ± 0.4 |
| R15 α-spectrin | 1.6 ± 0.1 | 3.91 ± 0.04 | 6.4 ± 0.5 | 1.4 ± 0.1 | 3.88 ± 0.04 | 5.4 ± 0.4 |
| R16 P60A α-spectrin | 1.8 ± 0.3 | 3.38 ± 0.05 | 6.2 ± 0.7 | 2.0 ± 0.2 | 3.43 ± 0.03 | 6.9 ± 0.6 |
| R1516 α-spectrinb | 1.6 ± 0.1 | 4.91 ± 0.03 | 7.9 ± 0.4 | 1.7 ± 0.1 | 4.92 ± 0.03 | 8.5 ± 0.5 |
Protein names denoted as in Fig. S6.
a
The pre-transition baseline was poorly defined for this protein. Thus, its slope was set to zero to aid curve fitting.
b
The two domains of the tandem R1516 α-spectrin construct unfold sequentially. However, this behaviour is not detected in equilibrium denaturant titrations (which appear 2-state). Thus, a 2-state equation was used for curve fitting only to allow the comparison of apparent [Denaturant]50% and mD–N values obtained using different titration strategies.