Cyclooxygenase

Cyclooxygenase refers to the oxygenating activity of prostaglandin-endoperoxide synthases, commonly distinguished as COX-1 and COX-2. These enzymes convert arachidonic acid through prostaglandin intermediates toward products used in local signalling. Their cyclooxygenase and peroxidase reactions are successive catalytic activities, rather than the names of two unrelated complete pathways. ^[ref]

Different tissues can process the common intermediate into different final signals, so inhibiting the upstream enzyme can affect several products at once. COX-1 and COX-2 also differ in their regulation and tissue distribution. A change in enzyme abundance, catalytic inhibition and a change in downstream product formation are related but experimentally distinct observations.