Trimethoprim inhibits which enzyme?
Answer and explanation
Correct answer: B. Dihydrofolate reductase
- Step 1: Trimethoprim blocks bacterial dihydrofolate reductase, which makes tetrahydrofolate. Step 2. Sulfamethoxazole blocks the step before it, so the combination is synergistic. Answer: dihydrofolate reductase. Why not the others: dihydropteroate synthase is the sulfonamide target, and the other enzymes are targets of fluorouracil and quinolones.
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