Question

A graph showing the effect of substrate concentration $\left[S\right]$ on enzyme activity is given below.
The correct statement(s) is/ are

• A. The reaction velocity reaches a maximum at low substrate concentation
• B. If a competitive inhibitors binds to the active site of the enzyme, it would not change the maximum velocity
• C. If an inhibitor that closely resembles the substrate binds to the active site of the enzyme, it would increase the $K_m$ of the reaction
• D. In the presence of a competitive inhibitor, increasing substrate concentration will not

Answer 1

Answer: (B), (C)

The correct options are
B If a competitive inhibitors binds to the active site of the enzyme, it would not change the maximum velocity
C If an inhibitor that closely resembles the substrate binds to the active site of the enzyme, it would increase the $K_m$ of the reaction

The graph is for competitive inhibition where competitive inhibitors are structural analogues of the substrate. They compete with the substrate for the active site. So, the inhibitor changes K${}_m$ but does not affect the Vmax.

They increase K${}_m$ by interfering with the binding of the substrate. More the resemblance of the inhibitor with the substrate, more increase in the value of K${}_m$.

Thus, the correct answers are options B and C.