COXenzymen

COXenzymen is a term used to describe the cyclooxygenase enzyme family, a group of heme-containing enzymes that catalyze the first committed step in the biosynthesis of prostanoids from arachidonic acid. In mammals this family comprises two best-characterized isoforms, COX-1 and COX-2, which form homodimers that reside mainly on the endoplasmic reticulum and the nuclear envelope. A proposed third variant, sometimes discussed as COX-3, has been reported in several species and as a splice variant of COX-1, but its activity in humans remains uncertain.

COXenzymen convert arachidonic acid, released from membrane phospholipids by phospholipase A2, into prostaglandin G2, which is rapidly reduced to prostaglandin H2 by the peroxidase activity within the same enzyme complex. PGH2 then serves as a substrate for various synthases to produce prostaglandins, thromboxanes, and prostacyclin, each with distinct biological roles in inflammation, hemostasis, and vascular function.

Regulation of COXenzymen expression and activity is context-dependent. COX-1 is generally constitutive, supporting routine physiological functions such as gastric mucosal protection and platelet aggregation. COX-2 is inducible by inflammatory stimuli, cytokines, and growth factors, contributing to pain and swelling. Activity can also be modulated post-translationally by phosphorylation and by cellular levels of arachidonic acid.

Pharmacologically, COXenzymen are targets of nonsteroidal anti-inflammatory drugs (NSAIDs) that reduce prostanoid synthesis. Nonselective inhibitors affect both COX-1 and COX-2, while COX-2 selective inhibitors aim to reduce inflammation with fewer gastric side effects, though they carry cardiovascular considerations.