Arachidonic Acid - Synthesis and Cascade

Synthesis and Cascade

Arachidonic acid is freed from a phospholipid molecule by the enzyme phospholipase A2 (PLA2), which cleaves off the fatty acid, but can also be generated from DAG by diacylglycerol lipase.

Arachidonic acid generated for signaling purposes appears to be derived by the action of a phosphatidylcholine-specific cytosolic phospholipase A2 (cPLA2, 85 kDa), whereas inflammatory arachidonic acid is generated by the action of a low-molecular-weight secretory PLA2 (sPLA2, 14-18 kDa).

Arachidonic acid is a precursor in the production of eicosanoids:

  • The enzymes cyclooxygenase and peroxidase lead to prostaglandin H2, which in turn is used to produce the prostaglandins, prostacyclin, and thromboxanes.
  • The enzyme 5-lipoxygenase leads to 5-HPETE, which in turn is used to produce the leukotrienes.
  • Arachidonic acid is also used in the biosynthesis of anandamide.
  • Some arachidonic acid is converted into hydroxyeicosatetraenoic acids (HETEs) and epoxyeicosatrienoic acids (EETs) by epoxygenase.

The production of these derivatives and their action in the body are collectively known as the "arachidonic acid cascade"; see essential fatty acid interactions for more details.

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