TABLE 1

Steady-state kinetics analysis: CPA metabolism catalyzed by P450s 2B1, 2B4, and 2B5

4-Hydroxylation N-Dechloroethylation
P450 KmVmaxVmax/KmKmVmaxVmax/Km % N-deCla
mM mol/min/mol mol/min/mol mM mol/min/mol mol/min/mol
P450 P450/mM P450 P450/mM
2B1b 1.45 ± 0.24 35.9 ± 6.2 24.9 ± 3.8 1.65 ± 0.09 1.1 ± 0.3 0.7 ± 0.2 3.2 ± 1.6
2B4c 5.28 ± 0.37 13.5 ± 2.9 2.6 ± 0.4 N.D. 0 0 0
2B5c 4.17 ± 1.82 2.8 ± 0.7 0.7 ± 0.1 N.D. 0 0 0

  • N.D., not determined; catalytic activity at or below limit of detection.

  • ↵ a N-dechloroethylation as a percentage of total metabolism at Vmax.

  • ↵ b Data are based on n = 4 independent experiments (4-hydroxylation) or n = 3 (N-dechloroethylation).

  • ↵ c Data are based on n = 2 independent experiments.