Which enzyme does trimethoprim inhibit?

Trimethoprim is an antibiotic that inhibits dihydrofolate reductase, an enzyme critical in the bacterial synthesis of folate. Dihydrofolate reductase catalyzes the reduction of dihydrofolate to tetrahydrofolate, which is an important cofactor in the synthesis of nucleic acids and thus essential for bacterial growth and replication. By inhibiting this enzyme, trimethoprim effectively reduces the availability of tetrahydrofolate, leading to impaired DNA synthesis and ultimately bacterial cell death.

The other enzymes mentioned are not the targets of trimethoprim. Beta-lactamase is involved in bacterial resistance to beta-lactam antibiotics, HMG-CoA reductase is a target for statin drugs used to lower cholesterol, and DNA gyrase is inhibited by fluoroquinolones, another class of antibiotics. Understanding these distinctions is crucial in pharmacology and can aid in effective therapeutic decision-making.