Table 3.
Kinetic parameters of the wild-type tyrosinase and mutant enzymes for l-tyrosine hydroxylation and l-dopa oxidation reactions.
| Enzyme |
l-Tyrosine |
l-Dopa |
||||
|---|---|---|---|---|---|---|
|
Km (μM) |
kcat (s−1) |
kcat/Km (μM−1 s−1) |
Km (mM) |
kcat (s−1) |
kcat/Km (mM−1 s−1) |
|
| Wild type | 1.32 ± 0.12 | 0.61 ± 0.025 | 0.46 | 0.34 ± 0.08 | 34.1 ± 2.3 | 100.3 |
| H180A | 1.81 ± 0.12 | 0.34 ± 0.012 | 0.19 | 0.42 ± 0.07 | 28.5 ± 1.9 | 67.9 |
| H202A | 1.63 ± 0.11 | 0.42 ± 0.017 | 0.26 | 0.45 ± 0.07 | 30.0 ± 2.5 | 66.7 |
| H211A | 1.44 ± 0.07 | 0.50 ± 0.043 | 0.34 | 0.37 ± 0.09 | 32.4 ± 3.1 | 87.6 |
| H363A | 1.99 ± 0.08 | 0.44 ± 0.01 | 0.22 | 3.09 ± 0.12 | 17.2 ± 1.3 | 5.6 |
| H367A | 1.77 ± 0.15 | 0.48 ± 0.011 | 0.27 | 3.20 ± 0.09 | 15.8 ± 1.0 | 4.9 |
| H389A | 1.67 ± 0.10 | 0.63 ± 0.018 | 0.38 | 0.24 ± 0.05 | 38.4 ± 1.2 | 160.0 |
| H390A | 1.47 ± 0.13 | 0.52 ± 0.017 | 0.35 | 0.36 ± 0.07 | 29.7 ± 1.3 | 82.5 |
Values are means ± SD, generally based on n ≥ 5.