Suicide inhibitor

Suicide inhibitors are a unique class of enzyme inhibitors that irreversibly inhibit their target enzyme by undergoing a reaction to form a covalently bonded complex. This process is also known as a mechanism-based inhibition.

Mechanism

The mechanism of action of suicide inhibitors involves the initial recognition and binding to the enzyme's active site, followed by the formation of a chemically reactive intermediate. This intermediate then reacts with the enzyme to form a covalent bond, thereby irreversibly inactivating the enzyme. This process is distinct from other forms of enzyme inhibition, such as competitive inhibition, non-competitive inhibition, and uncompetitive inhibition, which do not involve the formation of a covalent bond.

Examples

One of the most well-known examples of a suicide inhibitor is penicillin. Penicillin binds to the active site of the bacterial enzyme transpeptidase, which is involved in cell wall synthesis. The binding of penicillin triggers a reaction that results in the formation of a covalent bond with the enzyme, thereby irreversibly inhibiting its activity and preventing the synthesis of the bacterial cell wall.

Another example is aspirin, which acts as a suicide inhibitor of the enzyme cyclooxygenase. Aspirin acetylates a serine residue in the active site of cyclooxygenase, forming a covalent bond and irreversibly inhibiting the enzyme's activity. This results in the reduction of prostaglandin synthesis, which is involved in inflammation and pain signaling.

Clinical significance

Suicide inhibitors have significant clinical implications, particularly in the field of pharmacology and drug design. Because they irreversibly inhibit their target enzymes, they can provide long-lasting effects even after the drug has been cleared from the body. This makes them particularly useful in the treatment of chronic conditions. However, their irreversible nature also means that they must be used with caution, as overuse can lead to permanent loss of essential enzyme activity.

See also

• Enzyme inhibitor
• Enzyme kinetics
• Drug design