Para-Aminobenzoate synthase

Edman ]C, Goldstein AL, Erbe JO. para Aminobenzoate synthase gene of Sacdwtomyces cerevisUie encodes a bifunctional enzyme. Yeast 1993 9 669-675. 

Finally, sulfonamides can interfere with intermediary metabolism. Because of their structural similarity to para-aminobenzoic acid (PABA), they can function as competitive inhibitors for dihydropteroate synthase. The result is interruption of microbial synthesis of folic acid by blocking formation of the folic acid precursor dihydropteroic acid. Sensitive microorganisms are those that must synthesize their own folic acid. Conversely, resistant bacteria and normal mammalian cells are unaffected since they do not synthesize folic acid but use the preformed vitamin. 

Because Mycobacterium leprae does not grow on artificial media, in vivo assays with rat footpads have been used to test potential therapeutic agents. Dapsone is bacteriostatic for M. leprae due to competitive inhibiton of dihydropteroate synthase, which prevents bacterial utilization q/ para-aminobenzoic acid. 

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