Kinetics of the time-dependent inhibition of COX-2 by compound 7. The purified mCOX-2 enzyme was reconstituted with heme and pre-incubated with the inhibitor at 37 °C for various times (0, 0.5, 1, 3, 5, 10, 15, 30, 45, 60 and 120 min) prior to the addition of the substrate (50 μM). (A) Time-dependent inhibition of COX-2 by compound 7 at the indicated concentrations. (B) Secondary plot of kobs versus inhibitor concentration used to generate values for KI, k2 and k−2 using eqs 1 and 2 (see text).