Which drug groups compete with PABA for receptor binding?

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Multiple Choice

Which drug groups compete with PABA for receptor binding?

Explanation:
PABA analogs compete for the active site of the bacterial enzyme dihydropteroate synthase in the folate synthesis pathway. Sulfonamides are structural mimics of PABA, so they bind to this enzyme and competitively inhibit the condensation step needed to form dihydropteroic acid. This blocks folate production in bacteria, which impairs DNA synthesis and growth. Other options act on different targets—macrolides and tetracyclines affect the ribosome, and penicillins inhibit cell wall synthesis—so they don’t compete with PABA for binding.

PABA analogs compete for the active site of the bacterial enzyme dihydropteroate synthase in the folate synthesis pathway. Sulfonamides are structural mimics of PABA, so they bind to this enzyme and competitively inhibit the condensation step needed to form dihydropteroic acid. This blocks folate production in bacteria, which impairs DNA synthesis and growth. Other options act on different targets—macrolides and tetracyclines affect the ribosome, and penicillins inhibit cell wall synthesis—so they don’t compete with PABA for binding.

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