Question

$K_i$ of a competitive inhibitor indicates

• A. Affinity of the inhibitor towards the enzyme
• B. Affinity of the inhibitor towards the substrate
• C. Reaction velocity
• D. All the above

Answer 1

Answer: (A)

Affinity of the inhibitor towards the enzyme

ki indicates the affinity of the inhibitor to bind with the enzyme in case of competitive inhibition. A low value of Ki indicates that the affinity of inhibitor to bind with the enzyme is high and it is needed in lower concentration to reach a certain inhibition. A high value of Ki indicates its low affinity for enzyme and thus high concentration of inhibitor is needed to reach a certain inhibition. All this happens in case of competitive inhibition where the inhibitor competes with the substrate for the active site of enzyme as the inhibitor.

Thus, the correct answer is option A.