synthase (PGHS), at two different sites on the enzyme.
Arachidonic acid is initially cyclized and oxidized to the endoperoxide PGG2 at the cyclooxygenase site of the COX and the product then reduced to a second endoperoxide PGH2 at the peroxidase site. Subsequent formation of prostaglandin end products from PGH2 depends on the presence of specific synthases that produce the functionally importa