Table 2. Thermodynamic parameters for xylosaccharide and xylan binding to IXT6(E134Q).
| Ligand | T, °C | Ka × 104, M-1 | Kd (1/Ka), μM | ΔHa, kcal/mol | TΔSa, kcal/mol | ΔGa, kcal/mol | ΔCp, cal/mol K |
|---|---|---|---|---|---|---|---|
| Xylosaccharides | |||||||
| X2 | 20 | 2.5 ± 0.2 | 40 | -3.9 ± 0.09 | 2.0 | -5.9 | |
| 30 | 1.6 ± 0.6 | 63 | -3.2 ± 0.8 | 2.7 | -5.9 | -1 ± 14 | |
| 40 | 1.3 ± 0.8 | 77 | -3.6 ± 0.1 | 2.3 | -5.9 | ||
| 50 | 1.6 ± 0.2 | 63 | -3.9 ± 0.2 | 2.3 | -6.2 | ||
| X3 | 20 | 5.8 ± 0.3 | 17 | -4.1 ± 0.04 | 2.3 | -6.4 | |
| 30 | 4.3 ± 0.5 | 23 | -4.8 ± 0.3 | 1.7 | -6.5 | -90 ± 14 | |
| 40 | 3.6 ± 0.3 | 28 | -5.6 ± 0.1 | 0.9 | -6.5 | ||
| 50 | 3.3 ± 0.7 | 30 | -6.9 ± 0.2 | -0.2 | -6.7 | ||
| X4 | 20 | 28 ± 1.2 | 3.6 | -5.7 ± 0.02 | 1.6 | -7.3 | |
| 30 | 20 ± 0.2 | 5.0 | -8.2 ± 0.3 | -0.8 | -7.4 | -253 ± 18 | |
| 40 | 11 ± 0.3 | 9.1 | -10.4 ± 0.05 | -3.2 | -7.2 | ||
| 50 | 7.5 ± 0.4 | 13 | -13.4 ± 0.1 | -6.2 | -7.2 | ||
| X5 | 20 | 78 ± 7.6 | 1.3 | -6.7 ± 0.06 | -1.2 | -7.9 | |
| 30 | 47 ± 5 | 2.1 | -7.9 ± 0.1 | 0.0 | -7.9 | -242 ± 28 | |
| 40 | 30 ± 1.8 | 3.3 | -11.5 ± 0.1 | -3.6 | -7.9 | ||
| 50 | 19 ± 0.7 | 5.3 | -13.6 ± 0.06 | -5.8 | -7.8 | ||
| X6 | 20 | 112 ± 10 | 0.89 | -6.4 ± 0.04 | -1.8 | -8.2 | |
| 30 | 49 ± 5.8 | 2.0 | -7.4 ± 0.1 | 0.5 | -7.9 | -244 ± 34 | |
| 40 | 39 ± 3.5 | 2.6 | -11.4 ± 0.1 | -3.4 | -8.0 | ||
| 50 | 17 ± 0.5 | 5.9 | -13.2 ± 0.07 | -5.4 | -7.8 | ||
| Xylans | |||||||
| Beech wood | 30 | 42 ± 2.7 | 2.4 | -6.2 ± 0.04 | 1.5 | -7.9 | |
| Birch wood | 30 | 42 ± 4.2 | 2.4 | -4.7 ± 0.03 | 3.1 | -7.8 |