TABLE 3.
Kinetic and thermodynamic parameters of GtCPES·bilin complex formation
Association rate constant (kon) was obtained by stopped flow experiments and stoichiometry value (N), association constant (Ka), enthalpy (ΔH0), and entropy change (ΔS0) via ITC measurements. From those values, Kd = 1/Ka and koff = kon × Kd were calculated. ITC results with 3(E)-PEB were averaged over two measurements; ITC with 3(Z)-PEB was performed once due to insufficient amounts of bilin. ND means not determined.
| Bilin | kon | Ka | Kd | koff | ΔH0 | ΔS0 | N |
|---|---|---|---|---|---|---|---|
| μm−1 s−1 | ×106m−1 | μm | s−1 | kcal mol−1 | cal mol−1 K−1 | ||
| DHBV | 1.3 ± 0.3 | ND | ND | ND | ND | ND | ND |
| 3(E)-PEB | 2.1 ± 0.1 | 1.7 ± 0.9 | 0.6 ± 0.3 | 1.5 | −4.2 ± 2 | 13.4 ± 7.7 | 0.6 ± 0.3 |
| 3(Z)-PEB | 2.6 ± 0.1 | 1.7 | 0.6 | 1.5 | −3.2 | 17.5 | 1. 3 |