Table 4.
Kinetic constants for complexes of RI mutants
| RI | kd s−1 | ka, M−1·s−1 | Ki, M | Ki,mut*Ki,wt | ΔΔG† kcal/cal |
|---|---|---|---|---|---|
| RNase A complexes | |||||
| wt | 1.2 × 10−5 | 3.8 × 108 | 3.1 × 10−14 | ||
| Y434A | 7.2 × 10−10 | 23,000 | 5.9 | ||
| D435A | 1.5 × 10−11 | 470 | 3.6 | ||
| Y437A | 7.4 × 10−4 | 2.8 × 108 | 2.6 × 10−12 | 84 | 2.6 |
| Des460 | 2.9 × 10−3 | 2.5 × 108 | 1.2 × 10−11 | 387 | 3.5 |
| Ang complexes | |||||
| wt | 1.1 × 10−7 | 2.8 × 108 | 3.9 × 10−16 | ||
| Y434A | 7.3 × 10−6 | 7.6 × 107 | 9.6 × 10−14 | 246 | 3.3 |
| D435A | 1.4 × 10−5 | 1.0 × 108 | 1.4 × 10−13 | 358 | 3.5 |
| Y437A | 3.1 × 10−7 | 2.0 × 108 | 1.6 × 10−15 | 4.1 | 0.8 |
| Des460 | 6.3 × 10−7 | 1.9 × 108 | 3.3 × 10−15 | 8.5 | 1.3 |
*
Ki for mutant RI divided by Ki for wtRI.
†
Difference in free energies of binding wt and mutant RIs, calculated from the equation ΔΔG = −RTln(Ki,wt/Ki,mut). ΔG values for the native RNase A and Ang complexes are −18.4 kcal/mol and −21.0 kcal/mol, respectively.