Question

methotrexate is a drug that is commonly used to treat cancers and autoimmune diseases in humans. it functions by binding to the active site of the enzyme dhfr, preventing both dna synthesis and excess cell proliferation.

which of the following terms best describes methotrexate?

choose 1 answer:

a cofactor

b allosteric activator

c competitive inhibitor

d noncompetitive inhibitor

Explanation:

A competitive inhibitor binds to the active site of an enzyme, blocking substrate access and inhibiting enzyme function, which matches how methotrexate acts on DHFR. Cofactors assist enzyme function, allosteric activators enhance enzyme activity, and noncompetitive inhibitors bind to sites other than the active site, so these do not fit.

Answer:

C. Competitive inhibitor