Fig. 5.

Instantaneous inhibition of huPGHS-2-mediated oxygenation of 2-AG and 2-AG ether by IBP. The indicated concentrations of ibuprofen were present in a standard O₂ electrode assay mixture along with 25 μM 2-AG (A) or 25 μM 2-AG ether (B) as COX substrates. Purified huPGHS-2 was added to initiate oxygenation reactions. O₂ consumption was monitored as described in the Experimental Procedures. Results are shown for a single experiment involving triplicate determinations. The error bars indicate the average ± SD. When control values are normalized to 100% activity, significant differences from the control value (with no ibuprofen) were seen at all the ibuprofen concentrations tested, as determined by the Student’s t-test (P < 0.05). IC₅₀ values shown in the two panels were calculated using GraphPad Prism software. For the monophasic mode shown in the two panels in this figure, IC₅₀ values were calculated by using nonlinear regression to fit the data to the log [ibuprofen] versus normalized response (variable slope) curve.