Being impermeable to folic acid, many bacteria must rely on their ability to synthesise folate from PABA, Pteridine, and glutamate in contrast the mammalian in cells cannot synthesise folic acid and must obtain preformed folate as a vitamin in their diet. The sulphonamides are structurally similar to PABA, the sulphonamides competitively inhibit dihydropteroate synthetase, the enzyme that catal...