Table 1.
Thermodynamic parameters of the Arkadia constructs and mutants’ interaction with the E2 enzymes and their mutants obtained by ITC at 25 °C.
| Protein | Titrant | Kd (μM) | N | ΔG (Kcal/mol) | ΔH (Kcal/mol) | −TΔS (Kcal/mol) |
|---|---|---|---|---|---|---|
| Ark RING | UbcH5B | 32 ± 2 | 1 | −6.1 | 3.1 | −9.3 |
| Ark LONG | UbcH5B | 2.7 ± 0.5 | 0.6 | −7.6 | −4.7 | −2.9 |
| Ark LONG R983A | UbcH5B | 8.4 ± 0.4 | 0.7 | −6.9 | −5.8 | −1.1 |
| Ark LONG R983K | UbcH5B | 5.5 ± 0.6 | 0.5 | −7.2 | −3.6 | −3.6 |
| Ark RING | UbcH5B F62A | 130 ± 17 | ND | −5.3 | 3.6 | −8.9 |
| Ark LONG | UbcH5B F62A | 194 ± 24 | ND | −5.0 | 2.9 | −7.9 |
| Ark RING | UbcH7 | 27.3 ± 2 | 0.9 | −6.2 | 2.2 | −8.4 |
| Ark LONG | UbcH7 | 4.3 ± 0.5 | 0.7 | −7.3 | −0.7 | −6.5 |
| Ark RING | UbcH7 K96S | 10.2 ± 0.6 | 1 | −6.8 | −0.9 | −5.8 |
| Ark RING | UbcH13 | 264 ± 46 | 1.1 | −4.8 | 3.4 | −8.3 |
| Ark LONG | UbcH13 | 51.9 ± 5 | 0.9 | −5.8 | −2.3 | −3.5 |
Each value is the average of at least three independent measurements. Abbreviations: N, stoichiometry; Kd, dissociation constant; ΔH, ΔS, and ΔG, changes in binding enthalpy, binding entropy, and Gibbs energy, respectively.