Figure 1

Schematic diagram showing the peroxidase activity of PGHS. The process requires prior formation of a tyrosine radical from a tyrosine residue in close proximity to the haem group (Tyr 385). The tyrosyl radical is either recycled or participates in the suicide inactivation of the enzyme (for review of this process see [39]. Following incorporation of oxygen and formation of PGG₂, the peroxidase reduces the peroxyl moiety to the equivalent alcohol. The process allows for the concomitant oxidation of spin-trap CPH to CP which is detected by EPR.