Sulfonamides resemble which substance?

Sulfonamides resemble PABA, or para-aminobenzoic acid, because they act as competitive inhibitors in the bacterial synthesis of folic acid. PABA is a vital precursor in this pathway, which bacteria use to synthesize folate, an essential nutrient for the production of nucleic acids and certain amino acids. By mimicking PABA's structure, sulfonamides can bind to the enzyme that would typically catalyze the conversion of PABA to folate, thereby blocking the pathway and ultimately inhibiting bacterial growth. This mechanism is a key aspect of how sulfonamides function as antibiotics. Understanding this similarity is crucial to grasping how these drugs can effectively target bacterial metabolism without affecting human cells, which do not synthesize folate in the same manner.