Table 3.
Comparison of the thermodynamic parameters and stoichiometry of binding (N) of the three operator sites binding to wild-type CsoRSl obtained from ITC
| DNA operator | N | KD (nM) | ΔGb (kcal mol−1) | ΔHb (kcal mol−1) | -TΔSb (kcal mol−1) |
|---|---|---|---|---|---|
| csoR-CON | 0.54 (0.06) | 120 (9) | −9.4 (0.5) | −13.8 (0.7) | 4.4 (0.7) |
| csoR-EXT | 0.56 (0.05) | 74 (9) | −9.7 (1.4) | −11.7 (1.7) | 2.0 (0.3) |
| copZA2-CON | 0.52 (0.04) | 107 (12) | −9.5 (1.2) | −18.1 (2.3) | 8.7 (2.2) |
| copZA2-EXT | 0.53 (0.03) | 57 (10) | −9.9 (0.6) | −13.5 (0.7) | 3.6 (1.0) |
| copZA1-CON | 0.55 (0.01) | 971 (86) | −8.2 (0.7) | −16.1 (1.4) | 7.9 (1.5) |
| copZA1-EXT | 0.19 (0.03)a | 11 (3)a | −10.9 (1.6)a | −32.0 (4.8)a | 21.1 (4.9)a |
| 0.56 (0.03)b | 162 (21)b | −9.3 (1.6)b | −9.1 (1.5)b | −0.1 (1.5)b | |
| copZA1-GTA up | 0.54 (0.02) | 96 (10) | −9.6 (0.08) | −19.6 (0.2) | 10.0 (0.2) |
| copZA1-GTA down | 0.53 (0.02) | 87 (14) | −9.6 (0.7) | −21.5 (1.6) | 11.9 (1.6) |
a,bParameters obtained from fitting the data to a two sets of sites site binding model, i.e. aN1 and bN2, aKD1 and bKD2 and so forth. The uncertainties are given in parenthesis and are the standard deviations determined from duplicate measurements.
Experiments were performed at 25°C and pH 7.5.