Comparison of tyrosyl radical, oxyferryl heme, and peroxidase inactivation kinetics of Fe-PGHS-1 during reaction with 15-HPETE. Fe-PGHS-1 (30 µM) in 100 mM KPi (pH 7.2), 0.04% octyl glucoside, and 10% glycerol was reacted with 20 equiv of 15-HPETE at room temperature. (A) Time course of residual peroxidase activity (♦; fit, ─), tyrosyl radical intensity (○; fit, ─ ─ ─), deconvoluted WD concentration (▲; fit, •••), and oxyferryl heme (─•─). (B) EPR spectra from reaction samples freeze-trapped at the indicated times. EPR conditions were the same as those described in the legend of Figure 6.