TABLE 1.
Apparent thermodynamic data from the chemical denaturation of Venus
Values were obtained from the best fit of the yellow fluorescence (YF), tyrosine fluorescence (Tyr), and far-UV CD (CD) data to a two-state model (see Equation 2). For the YF data acquired at lower pH values, the initial drop in fluorescence, which we have shown is not due to an unfolding event, was not included in the fit.
| Conditions | mD-N | [D]50% | ΔGD-NH2O | [D]50%a | ΔGD-NH2Oa |
|---|---|---|---|---|---|
| kcal mol−1m−1 | m | kcal mol−1 | m | kcal mol−1 | |
| pH 8.0 37 °C | |||||
| YF | 2.22 ± 0.06 | 5.10 ± 0.01 | 11.3 ± 0.3 | 5.11 ± 0.02 | 8.74 ± 0.04 |
| Tyr | 1.51 ± 0.07 | 5.24 ± 0.03 | 7.9 ± 0.3 | 5.21 ± 0.02 | 8.93 ± 0.04 |
| CD | 2.08 ± 0.26 | 5.04 ± 0.05 | 10.5 ± 1.3 | 5.07 ± 0.06 | 8.7 ± 0.1 |
| pH 8.0 | |||||
| YF | 1.83 ± 0.09 | 5.92 ± 0.03 | 10.8 ± 0.5 | 5.81 ± 0.02 | 9.9 ± 0.2 |
| Tyr | 1.75 ± 0.11 | 5.80 ± 0.04 | 10.1 ± 0.6 | 5.89 ± 0.02 | 10.1 ± 0.2 |
| CD | 1.83 ± 0.23 | 6.19 ± 0.15 | 11.2 ± 1.3 | 6.12 ± 0.03 | 10.5 ± 0.2 |
| pH 7.6 | |||||
| YF | 1.91 ± 0.17 | 5.85 ± 0.06 | 11.2 ± 0.9 | 5.72 ± 0.03 | 9.8 ± 0.2 |
| Tyr | 1.52 ± 0.08 | 5.93 ± 0.06 | 9.0 ± 0.4 | 5.77 ± 0.02 | 9.9 ± 0.2 |
| CD | 1.65 ± 0.19 | 5.08 ± 0.15 | 8.4 ± 1.0 | 5.81 ± 0.03 | 9.9 ± 0.2 |
| pH 6.6 | |||||
| YF | 1.99 ± 0.07 | 5.22 ± 0.02 | 10.4 ± 0.3 | 5.16 ± 0.04 | 8.8 ± 0.2 |
| Tyr | 1.25 ± 0.05 | 5.23 ± 0.02 | 6.6 ± 0.3 | 5.23 ± 0.02 | 8.9 ± 0.2 |
| CD | 2.09 ± 0.55 | 4.78 ± 0.08 | 10.3 ± 2.5 | 5.19 ± 0.04 | 8.9 ± 0.2 |
| pH 6.0 | |||||
| YF | 2.20 ± 0.08 | 3.61 ± 0.02 | 8.0 ± 0.3 | 3.52 ± 0.17 | 6.0 ± 0.3 |
| Tyr | 2.10 ± 0.12 | 3.23 ± 0.02 | 6.8 ± 0.4 | 3.19 ± 0.03 | 5.5 ± 0.1 |
| CD | 2.48 ± 0.61 | 3.26 ± 0.10 | 8.8 ± 2.2 | 3.16 ± 0.03 | 6.2 ± 0.2 |
a Data were calculated using a global fit using a shared mD-N value of 1.71 kcal mol−1 m−1.