enzyme - any of several complex proteins that are produced by cells and act as catalysts in specific biochemical reactions

Cox-1, cyclooxygenase-1 - an enzyme that regulates prostaglandins that are important for the health of the stomach lining and kidneys; "an unfortunate side effect of Nsaids is that they block Cox-1"

Cox-2, cyclooxygenase-2 - an enzyme that makes prostaglandins that cause inflammation and pain and fever; "the beneficial effects of Nsaids result from their ability to block Cox-2"