Table 1.
Kinetic-isotope effects and thermodynamic and kinetic parameters of the P3→F3 and F3→O4 reactions in the wild-type (WT), two-subunit (SUIII–) and Asn139Asp (N139D) mutant CytcOs. The parameters are extracted from the data shown in Fig. 4. The data with the Asn139Asp mutant CytcO at pH 10 are not shown in that figure.
| CytcO | H2O or D2O (pH meter) |
P3→F3 |
F3→O4 |
||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| KIE at RT | Ea (kcal/mol) | ΔH≠ (kcal/mol) | −TΔS (kcal/mol) | ΔG≠ (kcal/mol) | KIE at RT | Ea (kcal/mol) | ΔH≠ (kcal/mol) | −TΔS≠ (kcal/mol) | ΔG≠ (kcal/mol) | ||
| WT | H2O (7.5) | 5.4±0.6 | 4.8±0.6 | 6.3±0.4 | 11±1 | 12.0±0.8 | 11.4±0.8 | 1.07±0.05 | 12.5±1 | ||
| WT | D2O (7.5) | ~2.0 | 9.3±1.3 | 8.7±1.3 | 2.7±0.3 | 11±2 | ~7.7 | 13.0±0.9 | 12.4±0.9 | 1.19±0.09 | 13.6±1 |
| SUIII– | H2O (7.5) | 4.3±0.7 | 3.7±0.7 | 7.8±0.7 | 12±2 | 17.5±0.2 | 16.9±0.2 | –4.52±0.05 | 12.4±0.3 | ||
| SUIII– | D2O (7.5) | ~2.2 | 8.5±0.4 | 7.9±0.4 | 3.9±0.1 | 12±0.5 | ~5.2 | 17.2±0.4 | 16.6±0.4 | –3.27±0.07 | 13.3±0.5 |
| N139D | H2O (7.5) | 7.9±1.6 | 7.3±1.6 | 3.6±0.5 | 11±2 | 11.0±0.4 | 10.4±0.4 | 1.79±0.06 | 12.2±0.5 | ||
| N139D | D2O (7.5) | ~2.0 | 11±1 | 10±1 | 1.0±0.07 | 11±1.2 | ~7.0 | 15.5±0.4 | 14.9±0.4 | –1.79±0.05 | 13.1±0.5 |
| N139D | H2O (10) | 7±2 | 6±2 | 5±1 | 11±3 | 13.6±1 | 13±1 | 1.0±0.1 | 14.0±1.1 | ||