Which enzyme activity would be directly inhibited by the addition of methotrexate?
A) thymidine kinase
B) thymidylate synthase
C) dihydrofolate reductase
D) serine hydroxymethyltransferase

Question

Quizplus · Accepted Answer

Methotrexate is a folic acid antagonist that competes with the substrate dihydrofolate for binding to dihydrofolate reductase, which is responsible for converting dihydrofolate to tetrahydrofolate. This inhibition leads to a decrease in the production of thymidine monophosphate, which is required for DNA synthesis. Therefore, the addition of methotrexate would directly inhibit dihydrofolate reductase activity.

Which Enzyme Activity Would Be Directly Inhibited by the Addition