S-Oxygenation of methimazole by human MBP-FMO3
The oxygenation of methimazole was determined by monitoring the oxidation of NADPH associated with the S-oxygenation of methimazole as described under Materials and Methods. Data are mean ± standard deviation.
Enzyme | n | Km | Vmax | Vmax/Km |
|---|---|---|---|---|
| μM | nmol/min/nmol | ml/min/nmol | ||
| FMO3 MBP | 9 | 11.6 ± 0.29 | 58.6 ± 2.08 | 7.60 ± 0.0* (100%) |
| Lys158-FMO3 MBP | 7 | 10.3 ± 0.76 | 27.5 ± 0.50 | 2.67 ± 0.1* (35%) |
| His132-FMO3 MBP | 5 | 15.2 ± 1.26 | 49.7 ± 4.16 | 3.26 ± 0.0* (42%) |
| His132, Lys158-FMO3 MBP | 6 | 10.5 ± 1.46 | 19.5 ± 1.3 | 1.90 ± 0.3* (25%) |
| Gly308-FMO3 MBP | 4 | 16.6 ± 0.92 | 14.6 ± 3.68 | 0.87 ± 0.1* (11%) |
| Lys158, Gly308-FMO3 MBP | 9 | 12 ± 1.55 | 10.6 ± 0.89 | 0.89 ± 0.1* (12%) |
|
Pro360-FMO3 MBP
|
9
|
7.6 ± 2.05
|
184 ± 9.2
|
24 ± 5* (315%)
|
↵* p < 0.05 compared to the result obtained for wild-type MBP-FMO3.