TABLE 1.
Apparent kinetic parameters of PcHGD1 and PcHGD2 for MHQ, DMHQ, and HGAa
| Substrate | Km (μM) | kcat (s−1) | kcat/Km (s−1 mM−1) | |
|---|---|---|---|---|
| PcHGD1 | Methoxyhydroquinone | 49 ± 14 | 8.66 ± 0.84 | 177 |
| Dimethoxyhydroquinone | 993 ± 236 | 1.37 ± 0.40 | 1.38 | |
| Homogentisic acid | 628 ± 238 | 0.08 ± 0.02 | 0.12 | |
| PcHGD2 | Methoxyhydroquinone | 34 ± 4 | 1.02 ± 0.01 | 33 |
| Dimethoxyhydroquinone | 2,896 ± 821 | 0.99 ± 0.25 | 0.34 | |
| Homogentisic acid | – | – | – |
a
The activity levels of PcHGD1 and PcHGD2 were determined in the reaction mixtures (1.0 mL) containing 0.1–5 µM PcHGDs and 5 µL of a substrate solution (0–600 mM in dimethylsulfoxide) in 50 mM MES and MOPS (pH 6.25 and 6.75), 30°C. We used the initial velocity for 30 s after the addition of each substrate for the calculation of apparent kinetic parameters. Data are presented as mean ± standard error of three experiments.