Table 4.
Metal Content and Kinetic Parameters of NagA and Mutantsa.
| Mutant | Zn/Subunit | kcat (s−1) | Km (mM) | kcat/Km (M−1s−1) |
|---|---|---|---|---|
| Q59H/N61H | 1.5 | 1.2 ± 0.1 | 5.4 ± 0.5 | (2.2 ± 0.3) × 102 |
| Q59H | 1.3 | 32 ± 3 | 0.31 ± 0.06 | (1.0 ± 0.2) × 105 |
| Q59A | 0.9 | 10 ± 0.4 | 0.08 ± 0.01 | (1.3 ± 0.2) × 105 |
| N61H | 1.0 | 2.6 ± 0.1 | 1.7 ± 0.2 | (1.5 ± 0.2) × 103 |
| N61A | 0.9 | 24 ± 1 | 0.80 ± 0.05 | (3.0 ± 0.2) × 104 |
| E131Q | 0.1 | 0.7 ± 0.1 | 3.6 ± 1.1 | (1.9 ± 0.7) × 103 |
| E131A | 0.2 | 1.9 ± 0.3 | 0.15 ± 0.06 | (1.3 ± 0.5) × 104 |
| K139M | 0.9 | 49 ± 2 | 2.0 ± 0.2 | (2.5 ± 0.3) × 104 |
| H143N | 0.6 | 0.43 ± 0.02 | 2.1 ± 0.1 | (2.0 ± 0.1) × 102 |
| H143Q | 0.3 | 2.4 ± 0.1 | 0.33 ± 0.04 | 7.3 ± 0.9 × 103 |
| Y223F | 0.8 | 167 ± 15 | 0.76 ± 0.11 | (2.2 + 0.4) × 105 |
| H251N | 0.9 | 6.8 ± 0.4 | 2.7 ± 0.4 | (2.5 + 0.4) × 103 |
| D273N | 0.7 | < 0.02 | - | - |
| D273A | 0.8 | < 0.02 | - | - |
a
Kinetic parameters were determined at pH 7.5 and 30 °C from fits to equation 1 using compound 1 as the substrate.