Fig. 2.
Time- and concentration-dependent inactivation of CYP2A6 (A) and CYP2A13 (B) by the nicotine Δ5′(1′)iminium ion. Activity remaining refers to coumarin 7-hydroxylation activity measured in a secondary reaction at the indicated times. The Δ5′(1′)iminium ion concentrations are 0 (●), 50 (○), 75 (▾), 100 (▵), and 200 (■) μM for CYP2A6 and 0 (●), 5 (○), 10 (▾), 25 (▵), 50 (■), and 100 (□) μM for CYP2A13. Values are mean ± S.D. from three independent experiments performed in duplicate. The insets represent the double-reciprocal plot generated from the slopes of the lines at the various concentrations.