Fig. 1.

Time- and concentration-dependent inactivation of CYP2B6 by RU486. The inactivation of the EFC deethylation activity of CYP2B6 in the reconstituted system that was incubated with 0 (○), 2 (•), 3 (▿), 5 (▵), 10 (□), and 25 μM (▪) RU486 is shown. Aliquots were removed at the times indicated and assayed for residual activity as described under Materials and Methods. Inset, double reciprocal plots of the initial rates of inactivation as a function of the RU486 concentrations. The kinetic constants were determined from the double reciprocal plot. The data shown represent the average of three separate experiments done in duplicate that did not differ by more than 10%.