<prompt> Suicidal enzyme is:LipoxygenaseCycloxygenaseThromboxane synthase5Nucleotidase  <response>: Ans. B. CycloxygenaseCyclooxygenase is a Suicide Enzyme Switching off of prostaglandin activity is partly achieved by are markable property of cyclooxygenase -- that of self-catalyzed destruction; i.e., it is a suicide enzyme. Quickreview-CyclooxygenaseCyclooxygenase COX also called prostaglandin H synthaseInvolved in Prostanoid Prostaglandin Thromboxane and Prostacyclin synthesisThis enzyme has two activities, acyclo oxygenase and peroxidase.COX is present as two isoenzymes, COX-1 and COX-2.Drugs acting as inhibitors COXNSAID-Aspirin-inhibits COX-1 and COX-2.-Indomethacin and ibuprofen-inhibit cyclooxygenases by competing with arachidonate.-Coxibs--selectively inhibit COX-2-Some coxibs have been withdrawn or suspended from the market due to undesirable side effects and safety issues.Anti-inflammatory Corticosteroids-Transcription of COX-2-- but not of COX-1-- is completely inhibited by corticosteroids. 