A dihydropteroate synthetase inhibitor is a drug that inhibits the action of dihydropteroate synthetase. Most are sulfonamides.
In bacteria, antibacterial sulfonamides act as competitive inhibitors of the enzyme dihydropteroate synthetase, DHPS. DHPS catalyses the conversion of PABA (para-aminobenzoate) to dihydropteroate, a key step in folate synthesis. Folate is necessary for the cell to synthesize nucleic acids (nucleic acids are essential building blocks of DNA and RNA), and in its absence cells will be unable to divide. Hence the sulfonamide antibacterials exhibit a bacteriostatic rather than bactericidal effect.
Uses
Folate is not synthesized in mammalian cells, but is instead a dietary requirement. This explains the selective toxicity to bacterial cells of these drugs. These antibiotics are used to treat pneumocystis jiroveci pneumonia, urinary tract infections, and shigellosis.
Two examples are dapsone and sulfamethoxazole.[1]
Another example is the antimalarial sulfadoxine.[2]
References
- ^ Suling WJ, Seitz LE, Reynolds RC, Barrow WW (November 2005). "New Mycobacterium avium antifolate shows synergistic effect when used in combination with dihydropteroate synthase inhibitors". Antimicrob. Agents Chemother. 49 (11): 4801–3. doi:. PMID 16251337. PMC: 1280141. http://aac.asm.org/cgi/pmidlookup?view=long&pmid=16251337.
- ^ Triglia T, Menting JG, Wilson C, Cowman AF (December 1997). "Mutations in dihydropteroate synthase are responsible for sulfone and sulfonamide resistance in Plasmodium falciparum". Proc. Natl. Acad. Sci. U.S.A. 94 (25): 13944–9. PMID 9391132. PMC: 28412. http://www.pnas.org/cgi/pmidlookup?view=long&pmid=9391132.
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