Table 4.
Summary of the dissociation constants, the changes in the heat capacity upon binding, and the kinetic rate constants of the TRTK12 wild-type peptide and alanine variants binding to S100A2 at 25°C.
| Peptide | Kda μM | ΔCp, expb kJ·mol−1·K−1 | ΔCp, calcc kJ·mol−1·K−1 |
|---|---|---|---|
| TRTK12 | 48 ± 3 (43 ± 9) | −1.5 ± 0.1 | −1.5 ± 0.1 |
| TRTKM1 | 15.2 ± 1.0 (16 ± 1) | −0.8 ± 0.1 | −1.3 ± 0.1 |
| TRTKM5 | 131.0 ± 6.1 (N/A)c | −0.9 ± 0.1 | −1.3 ± 0.1 |
| TRTKM6 | 21.5 ± 4.0 (23 ± 3) | −0.7 ± 0.1 | −1.5 ± 0.1 |
| TRTKM9 | 45.0 ± 2.0 (17 ± 4) | −0.4 ± 0.1 | −1.5 ± 0.1 |
| TRTKM10d | - | - | - |
| TRTKM11 | 504 ± 9.7 (N/A)c | −1.6 ± 0.1 | −1.5 ± 0.1 |
a
Dissociation constants obtained using ITC. Values in parentheses were obtained using emission fluorescence assays.
b
The experimentally determined changes in the heat capacity upon binding (Figure 3).
c
Structure-based calculations (see Eq. 7) homology models based on the human S100A2 dimer binding to two peptides using PDB:3IQQ (44).
d
No detectable binding by ITC or emission fluorescence.