Table 2.
Thermodynamic parameters and the stoichiometry of binding (N) of the csoR operator site binding to wild-type (WT) CsoRSl and mutants obtained from ITC
| DNA | Protein | N | KD (nM) | ΔGb (kcal mol−1) | ΔHb (kcal mol−1) | -TΔSb (kcal mol−1) |
|---|---|---|---|---|---|---|
| csoR-CON | WT | 0.54 (0.06) | 120 (9) | −9.4 (0.5) | −13.8 (0.7) | 4.4 (0.7) |
| csoR-EXT | WT | 0.56 (0.05) | 74 (9) | −9.7 (1.4) | −11.7 (1.7) | 2.0 (0.3) |
| csoR-EXT | R54A | 0.24 (0.1) | 2062 (667) | −7.8 (3.9) | −5.4 (2.7) | −2.4 (0.2) |
| csoR-EXT | R129A | 0.75 (0.02) | 134 (13) | −9.4 (0.1) | −17.4 (1.2) | 8.1 (1.2) |
| csoR-EXT | R132A | 0.53 (0.1) | 309 (58) | −8.9 (1.2) | −11.1 (1.5) | 2.1 (0.2) |
The uncertainties are given in parenthesis and are the standard deviation determined from duplicate measurements.
Experiments were performed at 25°C and pH 7.5. The R57A and Q81A mutants did not give an ITC profile, and therefore no parameters are reported.