Table 2.
Thermodynamic Parameters for GuHCl-Induced Denaturation of DREAM in the Absence/Presence of Ca2+ and Mg2+
| ΔGN→I (kcal mol−1) | mN→I (kcal M−1 mol−1) | CN→I (M) | ΔGI→U (kcal mol−1) | mI→U (kcal M−1 mol−1) | CI→U (M) | ΔGN→U (kcal mol−1) | |
|---|---|---|---|---|---|---|---|
| ApoDREAM | 1.6 ± 0.1 | 0.8 ± 0.1 | 2.0 | 7.7 ± 0.8 | 1.3 ± 0.1 | 5.9 | 9.3 ± 0.8 |
| Mg2+DREAM | 1.7 ± 0.2 | 0.8 ± 0.1 | 2.1 | 8.4 ± 0.9 | 1.4 ± 0.2 | 6.0 | 10.1 ± 0.9 |
| Ca2+DREAM | 1.6 ± 0.3 | 0.6 ± 0.1 | 2.0 | 11.3 ± 0.1 | 1.7 ± 0.1 | 6.5 | 12.9 ± 0.3 |
| Ca2+Mg2+DREAM | 3.8 ± 0.4 | 1.2 ± 0.2 | 3.2 | 10.5 ± 1.2 | 1.6 ± 0.2 | 6.5 | 14.3 ± 1.3 |
The thermodynamic parameters were calculated using Eq. (4) where N, I, and U correspond to the native state, intermediate state, and unfolded state, respectively. ΔG is the standard free energy for the transition, m is the dependence of the free energy on the denaturant concentration, and CN→I and CN→U represent for denaturant concentration of half unfold from native to intermediate state and from intermediate state to unfolded state, respectively. GN→U represents the overall unfolding free energy from native to unfolded state. Errors were determined from standard deviations of at least three independent measurements.