TABLE 1.
Thermodynamic parameters at To = 37 °C obtained from global fitting of the model functions (see supplemental material) to the ITC binding data (Fig. 2) and urea denaturation data (Figs. 3 and 5)
| Process | Parametera/unit |
||||
|---|---|---|---|---|---|
| ΔG(To)o/kcal mol−1 | ΔH(To)o/kcal mol−1 | ΔCPo/kcal mol−1 K−1 | m/kcal mol−1m−1 | ||
| Fab binding to the binding site of TNF-α | −13.1 (±0.07)b | −17.8 (±0.1) | −0.78 (±0.01) | ||
| Urea unfolding of | |||||
| Fab | F ↔ FD | 23.8 (±0.7) | 38.8 (±1.5) | 0.8 (±0.1) | 3.6 (±0.1) |
| TNF-α | T3 ↔ I3 | 5.5 (±0.4) | 8.2 (±0.2) | 1.5 (±0.3) | 1.1 (±0.1) |
| I3 ↔ 3TD | 21.8 (±0.4) | 6.5 (±1.5) | −0.5 (±0.2) | 2.1 (±0.05) | |
| TNF-α-Fab complex | T3F3 ↔ ITF | 12.1 (±0.5) | 18.5 (±1.5) | 0.3 (±0.1) | 1.9 (±0.1) |
| ITF ↔ 3TD + 3FD | 126 (±2) | 166 (±5) | 5.6 (±0.4) | 12.8 (±0.1) | |
a ± values represent standard deviations estimated from diagonal elements of the corresponding variance-covariance matrixes.
b The corresponding value of the binding constant calculated as K(To) = exp(−ΔG(To)o/RT) = 1.7 (±0.3) × 109 m−1.