dihydropteroate synthase inhibitor

{{Short description|A drug that inhibits the action of dihydropteroate synthase}}

Dihydropteroate synthase inhibitors are drugs that inhibit the action of dihydropteroate synthase. They include sulfonamides, dapsone, and para-aminosalicylic acid.{{Cite book | title=Goodman and Gilmans The Pharmacological Basis of Therapeutics | date=26 October 2017 | edition=13th | publisher=McGraw Hill Education | isbn=9781259584749 | page=1078}}

Image:THFsynthesis pathway.svg

In bacteria, antibacterial sulfonamides act as competitive inhibitors of the enzyme dihydropteroate synthase, DHPS. DHPS catalyses the conversion of PABA (para-aminobenzoate) to dihydropteroate, a key step in folate synthesis.{{Cite book | last=Bauman | first=Robert W. | title=Microbiology: With Diseases by Body System | location=Boston | date=2015 | edition=4th | publisher=Pearson | isbn=9780321918550 | page=296}} 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.{{Cite web | title=Sulfonamides and Sulfonamide Combinations | work=Merck Veterinary Manual | access-date=2017-06-18 | url=http://www.merckvetmanual.com/pharmacology/antibacterial-agents/sulfonamides-and-sulfonamide-combinations}}