Table 2.
Thermodynamic and kinetic parameters for TT–RR binding in K+
| Temp. (°C) | Ka (M−1) × 105 | ΔG°obs (kcal/mol) | ΔH°obs (kcal/mol) | TΔS°obs (kcal/mol) | kon (M−1s−1) | koff (s−1) × 10−5 |
|---|---|---|---|---|---|---|
| 100 mM KCl | ||||||
| 5 | 52 (±3) | −8.5 (±0.1) | −35.1 (±3.8) | −26.6 (±3.8) | 550 (±60) | 10 (±1) |
| 15 | 5.9 (±0.7) | −7.6 (±0.2) | −34.9 (±2.8) | −27.3 (±2.8) | 530 (±90) | 95 (±14) |
| 150 mM KCl | ||||||
| 5 | – | – | −39.4 (±1.5) | – | 2290 (±200) | 3.9 (±0.3) |
| 10 | – | – | −38.7 (±1.6) | – | 2250 (±80) | 12 (±1) |
| 15 | 58 (±4) | −8.9 (±0.1) | −40.4 (±2.6) | −31.5 (±2.6) | 2300 (±70) | 38 (±8) |
| 20 | 18 (±1) | −8.4 (±0.1) | −40.6 (±1.7) | −32.2 (±1.8) | 2200 (±60) | 110 (±20) |
| 25 | 4.7 (±0.2) | −7.7 (±0.1) | −41.8 (±1.9) | −34.1 (±1.9) | 2190 (±90) | 440 (±30) |
| 200 mM KCl | ||||||
| 5 | – | – | −37.9 (±5.2) | − | 6080 (±200) | 3.2 (±0.3) |
| 10 | – | – | −37.1 (±3.3) | – | 6060 (±460) | 9.5 (±0.7) |
| 20 | 76 (±3) | −9.2 (±0.1) | −40.0 (±4.2) | −30.8 (±4.1) | 5680 (±1040) | 76 (±16) |
| 25 | 27 (±5) | −8.8 (±0.2) | −46.3 (±4.8) | −37.4 (±4.8) | 6170 (±370) | 180 (±50) |
| 30 | 9.4 (±6.9) | −8.3 (±0.1) | −43.9 (±4.2) | −35.7 (±4.3) | 5810 (±650) | 650 (±90) |
– not determined because ITC c-value greater than 200.