EPR spectra of tyrosyl radicals formed during reaction of PGHS-2, Y348F/Y504F PGHS-2, and PGHS-1 with EtOOH. Individual EPR spectra are scaled to the same amplitude and overlaid to facilitate line shape comparisons. (A) PGHS-2 (11.2 μM heme) in 100 mM KPi (pH 7.2), 0.1% Tween-20, and 10% glycerol was reacted at room temperature with 5 equiv of EtOOH for the indicated times. Data are from ref 27. (B) The Y348F/Y504F PGHS-2 double mutant (68 μM heme) in 100 mM KPi (pH 7.2), 50 μM phenol, 0.04% octyl glucoside, and 10% glycerol was reacted at room temperature with 15 equiv of EtOOH for the indicated times. (C) PGHS-1 (8.5 μM heme) in 100 mM KPi (pH 7.2), 0.1% Tween-20, and 10% glycerol was reacted at room temperature with 5 equiv of EtOOH for the indicated times. Data are from ref 27.