Question

Sulfa drug such as sulfonamide interferes with the synthesis of the vitamin niacin because sulfanilamide resembles nicotinic acid, which is a building block of this vitamin. This was used in the textbook as an example of non-competitive inhibition because the sulfanilamide binds to the allosteric regulatory site of the enzyme. True or False?

Answer 1

False. The claim about sulfanilamide acting as a non-competitive inhibitor is false. It is actually a competitive antagonist that inhibits bacterial growth by blocking folic acid synthesis.

Step-by-step explanation:

The statement that sulfanilamide binds to the allosteric regulatory site of the enzyme and serves as an example of non-competitive inhibition is false. Sulfonamides, such as sulfanilamide, are structural analogs and competitive antagonists of para-aminobenzoic acid (PABA), which means they compete with PABA for the active site of the bacterial enzyme involved in folic acid synthesis.

By acting as competitive inhibitors, sulfonamides block the synthesis of dihydrofolic acid, an essential component in the production of bacterial folic acid, ultimately inhibiting bacterial growth due to the inability to synthesize necessary nucleic acids and proteins.