Prostaglandin Synthesis

Eicosanoids are a class of compounds that mediate a variety of cellular responses. One group of eicosanoids is called prostaglandins. These compounds are produced by all cells and they cause the inflamatory reponse to injury and the production of pain and fever. They act like hormones and are often called hormones. They differ from true hormones in that they are produced by all cells and act locally.

Prosaglandins are made by cyclizing a 20 carbon polyunsaturated fatty acid called arachidonate. Recall that arachidonate is made from lineolate and we need to absorb linealoate from food because we can't make it ourselves. The most important reaction is the first one in the pathway. It is catalyzed by prostaglandin H synthase (PGHS) a key target for pain relief.

PGHS is a bifunctional enzyme, which means it carries out two separate reactions. The first reaction is a cyclization reaction converting arachidonate to a hydroperoxide called prostaglandin G₂. This activity is often called a cyclooxygenase (COX) activity. The second reaction is catalyzed at a different site, the hydroperoxidase site, and the final product is prostaglandin H₂.

Subsequent reactions lead to the synthesis of other prostaglandins and other eicosanoids. This is the pathway that earned Bergström, Samuelsson, and Vane the Nobel Prize in 1982.