Question

5. Sulfanilamides are a class of antibiotics that inhibit an enzyme involved in the synthesis of folic acid, which is necessary for the synthesis of purines and pyrimidines. A) Explain why inhibiting this enzyme would lead to the death of bacterial cells. B) Sulfanilamides are competitive inhibitors. Do you think that sulfanilamides are likely to bind reversibly or irreversibly to the enzyme? Explain your answer.

Answer 1

A. Sulfanilamides are organo-sulfur compounds with antibacterial activity. They compete with PABA for the active site on the bacterial enzyme dihydropteroate synthase thereby inhibiting the biosynthesis of folic acid. Folic acid is required for nucleotide biosynthesis. In the absence of folate, nucleic acid biosynthesis would not occur. DNA replication is a prerequisite for cell division. Hence, sulfanilamides inhibit bacterial proliferation by preventing DNA replication.

B. Sulfanilamides are competitive inhibitors i.e. they compete with the substrate for the same active site on the enzyme as the substrate. An increase in substrate concentration can alleviate competitive inhibition.
i.e. competitive inhibitors bind reversibly to the enzyme.

Please provide a POSITIVE RATING. Thank you