Cyclooxygenase-2 (COX-2) is an enzyme vital to the production of the prostaglandins, but also contributes to the inflammation of joints in medical conditions such as arthritis. New medications that block the production of prostaglandins by COX-2 enzymes and thereby relieve the symptoms of arthritis are a type of


Substances that compete to attach to an enzyme’s active site are called inhibitors. If they attach to the enzyme first, the cellular reaction (in this case the synthesis of prostaglandins) will not take place. A hormone is a specific chemical messenger used throughout the endocrine system. The COX-2 inhibitor is a molecule, not an ion. Prosthetic groups and cofactors are substances that work with enzymes to enhance certain reactions, whereas an inhibitor will limit the reaction.

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