Km and Vmax values for the oxidation of thiocarbamides catalyzed by human FMO1 expressed in insect cells
| Substrate | Km | Vmax |
|---|---|---|
| M | nmol substrate oxidized/min/mg | |
| Methimazole | 5 | 18.09 ± 0.46 |
| Thiourea | 4 | 21.12 ± 0.75 |
| Phenylthiourea | 3 | 20.16 ± 0.11 |
| 1,3-Diphenylthiourea | ND |
Activities were measured by following substrate-dependent thiocholine oxidation as described in the text. Also see Guo et al. (1992). Values are means ± S.E. of triplicate measurements for each preparation. Kinetic constants were obtained from reciprocal plots of velocity of substrate-dependent thiocholine oxidation versus substrate concentration above and below the concentration required to give half maximal velocity.
ND, activity not detected at the highest concentrations soluble in the reaction medium.