Enzyme inhibitors are molecules that interact with enzymes to regulate their activities.
They are vital for cellular control and pharmaceutical development, targeting specific enzymatic pathways to treat diseases.
Inhibitors can be classified based on their reversibility and mode of action.
Reversible Enzyme Inhibitors
Reversible inhibitors temporarily bind to enzymes and are classified into three types:
Competitive Inhibitors
Mechanism: Compete with the substrate for the active site due to structural similarity.
Overcoming Inhibition: Increasing substrate concentration can reduce inhibition.
Example: Methotrexate inhibits dihydrofolate reductase, used in cancer and autoimmune disease treatment.
Non-competitive Inhibitors
Mechanism: Bind to an allosteric site, causing conformational changes that reduce enzyme function.
Example: Allopurinol inhibits xanthine oxidase, reducing uric acid production to treat gout and prevent kidney stones.
Uncompetitive Inhibitors
Mechanism: Bind exclusively to the enzyme-substrate complex, preventing product release.
Example: Lithium ions inhibit inositol monophosphates, used in managing bipolar disorder.
Irreversible Enzyme Inhibitors
Irreversible inhibitors bind covalently to enzymes, causing permanent deactivation.
They often target critical amino acids in the active site.
Example: Aspirin irreversibly inhibits cyclooxygenase (COX) enzymes by acetylating a serine residue, blocking prostaglandin synthesis, and providing anti-inflammatory, analgesic, and antipyretic effects.