Table 2.
Kinetic parameters for benzydamine-N-oxidation by human liver microsomes and cDNA expressed FMO3, FMO1 and FMO5; Impact of genotype on enzyme activity in vitro.
| Kma | Vmaxb | ||||||
|---|---|---|---|---|---|---|---|
| HLM group | n | mean | median | 25 —15 percentile | mean | median | 25 —15 percentile |
| Total | 35 | 64.0 | 58.7 | 52.4–77.3 | 6.9 | 6.5 | 4.1–7.8 |
| EE158 | 14 | 65.3 | 72.2 | 49.0–82.3 | 7.3 | 6.9 | 5.7–7.9 |
| EK158 | 16 | 64.4 | 57.6 | 54.4–80.7 | 7.0 | 6.5 | 5.1–7.6 |
| KK158 | 5 | 58.7 | 57.2 | 54.7–63.4 | 5.0 | 2.7 | 2.3–6.3*) |
| VV257 | 29 | 62.2 | 57.8 | 51.6–75.5 | 6.5 | 6.3 | 3.9–7.3 |
| VM257 | 4 | 66.0 | 65.1 | 52.4–80.6 | 10.1 | 10.5 | 6.2–13.5 |
| MM257 | 2 | 84.8 | 84.8 | 82.3–87.3 | 5.5 | 5.5 | 3.4–7.6 |
| EE308 | 24 | 66.1 | 69.6 | 51.9–82.2 | 7.2 | 6.5 | 5.2–7.8 |
| EG308 | 11 | 59.4 | 57.2 | 52.4–62.6 | 6.1 | 5.7 | 2.8–7.8 |
| GG308 | 0 | ||||||
| Recombinant | |||||||
| FMO3 | 40.0 | 29.0 | |||||
| FMO1 | 24.0 | 41.0 | |||||
| FMO5 | no activity | no activity | |||||
*) vmax significantly reduced in homozygous samples (KK158) compared with those carrying at least one wild type allele (EE158 + EK158); P<0.05, Mann-Whitney-U-test. (Kruskal-Wallis-test for all three groups: P = 0.104, Chi square = 4.519, d.f. = 2) a: Km[μm] -Michaelis-Menten constant; b: Vmax [nmol mg−1 protein min−1].