Kinetic parameters of P450 2A3-catalyzed metabolism of racemic, (R)-, and (S)-NNN
| Substrate | Reaction | Km | Vmax |
|---|---|---|---|
| μM | nmol/min/nmol P450 | ||
| Racemic NNN1-a | Total α-hydroxylation | 13.0 ± 1.7 | 17.8 ± 1.0 |
| (S)-NNN1-b | 5′-Hydroxylation | 5.22 ± 0.61 | 9.34 ± 0.35 |
| (R)-NNN1-c | 2′-Hydroxylation | 18.7 ± 3.8 | 15.6 ± 0.9 |
| (R)-NNN | 5′-Hydroxylation | 11.3 ± 3.4 | 5.59 ± 0.43 |
Conditions of reactions and quantitation of products were as described under Materials and Methods. Values are mean ± S.E.
↵1-a NNN concentrations were 0.2, 0.4, 0.7, 0.8, 0.9, 1.7, 2.1, 3.2, 8, 15, 29, 34, 55, 74, 86, 103, 110, 190, and 360 μM.
↵1-b (S)-NNN concentrations were 0.3, 0.4, 0.6, 0.7, 1.1, 1.2, 1.3, 1.6, 1.9, 2.4, 9.7, 16, 48, and 94 μM.
↵1-c (R)-NNN concentrations were 0.2, 0.4, 0.7, 0.8, 1.2, 1.4, 1.6, 2.3, 3.5, 6.8, 8.8, 17, 43, 77, 91, 126, and 230 μM.