Table 2. Thermodynamic parameters for interaction between wild type/mutant ECP and heparin derivatives.
| Heparin | Protein | K D (nM) | ΔH (kcal/mol) | TΔS (kcal/mol) | N (sites) | ΔG (kcal/mol) |
|---|---|---|---|---|---|---|
| wtECP | 2025.1 ± 506.3 | -3 ± 0.2 | 4.8 ± 0.1 | 1.77 ± 0.1 | -7.8 ± 0.1 | |
| Hep6 | Q40A | 2597.4 ± 870.7 | -4.4 ± 0.3 | 3.2 ± 0.2 | 1.7 ± 0.1 | -7.6 ± 0.2 |
| (1,800 Da) | H64A | 2164.5 ± 1072.9 | -5.8 ± 0.4 | 2 ± 0.3 | 2.74 ± 0.3 | -7.7 ± 0.4 |
| Q40A/H64A | 2984 ± 536 | -3.9 ± 0.2 | 3.7 ± 0.1 | 2.45 ± 0.1 | -7.5 ± 0.1 | |
| R105A | 2057.6 ± 541.9 | -4.4 ± 0.2 | 3.3 ± 0.1 | 2.81 ± 0.1 | -7.9 ± 0.2 | |
| wtECP | 51.3 ± 7.7 | -37.2 ± 0.5 | -27.1 ± 0.9 | 0.33 | -10.2 ± 0.2 | |
| LMWH | Q40A | 124.4 ± 13.2 | -38.4 ± 1.6 | -29.2 ± 1.5 | 0.36 | -9.2 ± 0.3 |
| (~5,000 Da) | H64A | 78.7 ± 23.6 | -41.8 ± 1.5 | -32.2 ± 1.3 | 0.41 | -9.5 ± 0.5 |
| Q40A/H64A | 147.9 ± 16.9 | -35.5 ± 0.4 | -26.2 ± 1.3 | 0.52 | -9.3 ± 0.1 | |
| R105A | 33.3 ± 5.2 | -36.6 ± 0.3 | -32.5 ± 2.2 | 0.52 | -9.9 ± 0.3 | |
| wtECP | 16.4 ± 3.1 | -92.9 ± 1.9 | -82.6 ± 5.6 | 0.06 | -10.3 ± 0.2 | |
| HMWH | Q40A | 22.6 ± 4.8 | -103.6 ± 1.8 | -93 ± 7.5 | 0.14 | -10.2 ± 0.1 |
| (~10,000 Da) | H64A | 30.9 ± 8 | -116.8 ± 2.3 | -106.4 ± 12.8 | 0.19 | -10.4 ± 0.4 |
| Q40A/H64A | 34.7 ± 13.1 | -90 ± 2.7 | -79.9 ± 13.6 | 0.22 | -10.2 ± 0.3 | |
| R105A | 17.9 ± 6.4 | -113.6 ± 2.9 | -103.1 ± 10.4 | 0.32 | -10.5 ± 0.1 |
All experiments were performed at 25 °C in PBS, pH 7.4. Data are reported as the mean of three separate titrations ± SD. Hep6, heparin hexasaccharide.