Table 1.
Comparison of cAT and single tryptophan mutants.
| Variant | SI (pre-unfold) | SI (refold) | Tm (°C) | +GdnHCl Tm (°C) | D50% (M) | ∆GD-N (kcal mol−1) | |
|---|---|---|---|---|---|---|---|
| cAT | 1.5 ± 0.1 | 1.7 ± 0.1 | >95 | 69.9 ± 0.1 | Fl.CD | 2.9 (2.8)2.9 (2.8) | 23 ± 3 19 ± 3 |
| cATW160 | 1.5 ± 0.2 | 1.4 ± 0.2 | 82.2 ± 0.3 | 64.0 ± 0.1 | Fl.CD | 2.5 (2.6)2.6 (2.6) | 13 ± 3 13 ± 2 |
| cATW194 | 1.2 ± 0.1 | 1.1 ± 0.1 | 83.1 ± 0.3 | 64.1 ± 0.1 | Fl.CD | 2.5 (2.6)2.5 (2.5) | 18 ± 3 13 ± 2 |
| cATW275 | 1.5 ± 0.1 | 1.6 ± 0.1 | 77.6 ± 0.1 | 61.9 ± 0.1 | Fl.CD | 2.7 (2.7)2.6 (2.6) | 15 ± 2 11 ± 1 |
The SI was determined against chymotrypsin prior to unfolding in 6 M GdnHCl and after refolding by dilution back to a final GdnHCl concentration of 0.2 M. SI errors reflect ± SE from the fit to the data (n = 2 or 3). Thermal unfolding was monitored by the change in CD signal, in the absence and presence of 2 M GdnHCl; Tm errors are SEM from three independent experiments. Refold D50%, shown in parentheses, was derived by unfolding protein in 6 M GdnHCl and then diluting it back into 0.2 M GdnHCl; midpoint and ∆GD-N values were calculated from equilibrium unfolding intrinsic fluorescence and CD profiles, as indicated.