Question

Which one of the following parameters changes upon doubling the enzyme concentration?

• A. \( K_M \)
• B. \( V_{max} \)
• C. \( k_{cat} \)
• D. \( K_{eq} \)

Hint:

The \( V_{max} \) of an enzyme-catalyzed reaction is directly proportional to the enzyme concentration. Increasing the enzyme concentration increases the maximum velocity of the reaction.

Answer 1

The Correct Option is B

Step 1: Understanding enzyme kinetics.
The Michaelis-Menten constant \( K_M \) and the catalytic rate constant \( k_{cat} \) are intrinsic properties of the enzyme and do not change with enzyme concentration. However, \( V_{max} \), which represents the maximum reaction velocity, is directly proportional to enzyme concentration.
Step 2: Analyzing the options.
(A) \( K_M \): Incorrect — \( K_M \) is independent of enzyme concentration.
(B) \( V_{max} \): Correct — \( V_{max} \) increases when enzyme concentration is doubled.
(C) \( k_{cat} \): Incorrect — \( k_{cat} \) is a constant that does not change with enzyme concentration.
(D) \( K_{eq} \): Incorrect — \( K_{eq} \) is related to the equilibrium constant and does not depend on enzyme concentration.
Step 3: Conclusion.
The correct answer is (B) \( V_{max} \), as doubling the enzyme concentration increases \( V_{max} \).