TABLE 1.
Thermodynamic parameters for ITC experiments
0.5 mm divalent metal solution was titrated into 50 μm AnhE in 20 mm HEPES, pH 7.5 at 25 °C.
| N | Ka | Kd | ΔH | ΔS | ΔGa | Ka/Ka | ΔΔGb | Nc | |
|---|---|---|---|---|---|---|---|---|---|
| ×10−9m−1 | Nm | kcal mol−1 | cal mol−1K−1 | kcal mol−1 | Co | kcal mol−1 | |||
| First binding | |||||||||
| Co2+ | 0.48 ± 0.03 | 10 ± 5 | 0.12 ± 0.06 | −3.7 ± 0.2 | 32 ± 3 | −13.6 ± 0.9 | 1 | 5 | |
| Zn2+ | 0.478 ± 0.002 | 0.1 ± 0.02 | 11 ± 2 | −6.8 ± 0.2 | 13.7 ± 0.9 | −10.9 ± 0.1 | 0.01 | −2.7 | 3 |
| Ni2+ | 0.49 ± 0.06 | 0.22 ± 0.07 | 49 ± 17 | −7.9 ± 0.4 | 7 ± 2 | −10.0 ± 0.2 | 0.0022 | −3.6 | 5 |
| Second binding | |||||||||
| Co2+ | 0.42 ± 0.04 | 10 × 106 ± 4 × 106 | 110 ± 35 | 1.6 ± 0.4 | 36 ± 2 | −9.0 ± 0.8 | 1 | 5 | |
a ΔG = RT ln Ka, T = 298 K.
b ΔΔG = RT ln (Ka/Ka (co)).
c n = number of observations.