What conclusion can be drawn concerning an inhibitor if the KM is the same in the presence and absence of the inhibitor?
A) The inhibitor binds to the substrate.
B) The inhibitor has a structure that is not very similar to the substrate.
C) The inhibitor forms a reversible covalent bond with the enzyme.
D) The inhibitor binds to the same active site as the substrate.
E) The Vmax is larger in the presence of the inhibitor.

Question

Quizplus · Accepted Answer

If the KM is the same in the presence and absence of the inhibitor, it suggests that the inhibitor does not compete with the substrate for binding to the active site. If the inhibitor had bound to the active site, it would have caused an increase in the apparent KM. Therefore, the inhibitor likely has a structure that is not very similar to the substrate, and likely binds to a different site on the enzyme. This would be consistent with choice B, which suggests that the inhibitor does not bind to the active site.

What Conclusion Can Be Drawn Concerning an Inhibitor If the KM