Dihydropteroate synthetase inhibitor

Dihydropteroate synthetase inhibitors are a class of antibiotics that work by inhibiting the enzyme dihydropteroate synthetase. This enzyme is crucial in the synthesis of folic acid, which is necessary for the production of DNA and RNA in bacteria. By inhibiting this enzyme, these antibiotics prevent the bacteria from synthesizing folic acid, thereby inhibiting their growth and reproduction.

Mechanism of Action

Dihydropteroate synthetase inhibitors work by binding to the active site of the enzyme dihydropteroate synthetase. This prevents the enzyme from catalyzing the conversion of para-aminobenzoic acid (PABA) to dihydropteroic acid, a key step in the synthesis of folic acid. Without folic acid, the bacteria cannot synthesize DNA and RNA, and thus cannot reproduce.

Examples

One of the most well-known examples of a dihydropteroate synthetase inhibitor is sulfamethoxazole, which is often used in combination with trimethoprim, a dihydrofolate reductase inhibitor. This combination is known as co-trimoxazole, and is used to treat a variety of bacterial infections.

Other examples of dihydropteroate synthetase inhibitors include sulfadiazine, sulfisoxazole, and sulfapyridine. These antibiotics are often used to treat urinary tract infections, respiratory tract infections, and meningitis caused by susceptible bacteria.

Resistance

Resistance to dihydropteroate synthetase inhibitors can occur through several mechanisms. One common mechanism is the acquisition of a plasmid that encodes a resistant form of dihydropteroate synthetase. Another mechanism is the increased production of PABA, which can outcompete the inhibitor for binding to the enzyme.

Side Effects

Like all antibiotics, dihydropteroate synthetase inhibitors can have side effects. These can include nausea, vomiting, diarrhea, and skin rash. In rare cases, these antibiotics can cause serious side effects such as Stevens-Johnson syndrome and toxic epidermal necrolysis.

See Also

• Antibiotic resistance
• Sulfonamides
• Folic acid antagonist