Table 2. The effects of NAT, NAB and nicotine on the kinetic parameters of CYP2A13-catalyzed NNK metabolism a .
| NNK | NNK + NAT (1 μM) | NNK + NAB (1 μM) | NNK + nicotine (10 μM) | |
| K m (μM) | ||||
| OPB | 3.5 | 22.9 | 23.7 | 7.4 |
| HPB | 9.3 | 17.8 | 20.1 | 13.1 |
| OPBA | 4.1 | 15.5 | 14.5 | 11.0 |
| V max (pmol min–1 pmol–1 2A13) | ||||
| OPB | 6.3 | 6.6 | 7.0 | 6.3 |
| HPB | 10.6 | 9.7 | 10.9 | 10.8 |
| OPBA | 1.3 | 1.3 | 1.4 | 1.2 |
aMeans the reaction was performed at 37 °C for 5 min with NNK (1–100 μM), CYP2A13 (12.5 pM), a NADPH-generating system and MgCl2 (3 mM), in the absence or presence of NAT, NAB or nicotine.