Question

Consider the following statements regarding the Michaelis-Menten's constant $\left(K_m\right)$.
I: $K_m$ is indicative of the affinity of an enzyme for its substrate.
II: A high $K_m$ indicates high affinity for substrate binding.
III: $K_m$ is a measure of the substrate concentration required for effective catalysis to occur.
The correct statements are.

• A. Only I and II
• B. Only II and III
• C. Only I and III
• D. I, II and III

Answer 1

Answer: (C)

Only I and III

A basic theory of an enzyme action was proposed by Michaelis and Menten in 1913. They introduced a constant Km which is called Michaelis constant.

1. Km indicates the affinity of an enzyme for its substrate. Hence statement I is correct.

2. A high Km indicates low affinity while a low Km shows the strong affinity for substrate binding. Hence statement II is incorrect.

3. Km value differs from substrate to substrate because different enzyme differs in their affinity towards different substrates. Hence statement III is correct.

So, the correct answer is C.