Table 3.
Thermodynamic parameters
Titration experiments were done at 25 °C. NBD indicates no detectable binding.
| Species | Substrate | Kd | ΔGa | ΔH | TΔSb | ΔS | |
|---|---|---|---|---|---|---|---|
| μm | kcal/mol | kcal/mol | kcal/mol | cal/mol·K | |||
| a | MDDEF (100 μm) | MVAPP (2 mm) | 20.4 ± 9.3 | −6.5 ± 0.3 | −0.7 ± 0.1 | 5.8 ± 0.2 | 19.5 ± 0.5 |
| b | MDDEF (100 μm) | ATP (3 mm) | 288 ± 36 | −4.8 ± 0.1 | −3.8 ± 0.5 | 1.0 ± 0.3 | 3.5 ± 1.0 |
| c | MDDEF (100 μm) | ATPγS (3 mm) | 215 ± 8 | −5.00 ± 0.02 | −6.4 ± 0.3 | −1.4 ± 0.2 | −4.7 ± 0.6 |
| d | MDDEF (100 μm) + MVAPP (1 mm) | ATPγS (2 mm) | 25.4 ± 5.5 | −6.3 ± 0.1 | −4.8 ± 1.1 | 1.5 ± 0.6 | 5.0 ± 2.1 |
| e | MDDEF (100 μm) | AMPPCP (3 mm) | 271 ± 43 | −4.87 ± 0.09 | −3.20 ± 0.50 | 1.67 ± 0.36 | 5.61 ± 1.21 |
| f | MDDEF (100 μm) + MVAPP (1 mm) | AMPPCP (5 mm) | NDB | NDB | NDB | NDB | NDB |
| g | MDDEF (100 μm) +AMPPCP (1 mm) | MVAPP (2 mm) | 18.7 ± 7.4 | −6.50 ± 0.23 | 0.91 ± 0.18 | 7.41 ± 0.20 | 24.88 ± 0.69 |
a The mean of ΔG (μ) is derived from the equation: μ = −RTln(m/√1 + (v/m2)) and the standard deviation of ΔG (σ) is calculated from the equation: σ = RT√ln(1 + (v/m2)), where m is the mean of the association constant (Ka), and v is the variance of Ka derived from each ITC experiment.
b The mean of TΔS (μ1–2) is derived from the difference between the means of ΔG (μ1) and ΔH (μ2) and the standard deviation (σ1–2) of TΔS is derived from the equation: σ1–2 = √(σ12/n + σ22/n), where σ1 is the standard deviation of ΔG and σ2 is the standard deviation of ΔH.