Question

The degree of inhibition for an enzyme catalyzed reaction at a particular inhibitor concentration is independent of the initial substrate concentration. This is

• A. Un-competitive inhibition
• B. Non-competitive inhibition
• C. Competitive inhibition
• D. Mixed inhibition

Hint:

Non-competitive inhibition is characterized by the inhibitor binding to an allosteric site, affecting the enzyme's activity without depending on the substrate concentration.

Answer 1

The Correct Option is B

Step 1: Understand the inhibition types.
In enzyme kinetics, the type of inhibition affects how the inhibitor interacts with the enzyme and its active site.

Step 2: Analyze Non-competitive Inhibition.
In non-competitive inhibition, the inhibitor binds to an allosteric site on the enzyme, not the active site. This binding alters the enzyme's shape, reducing its ability to catalyze the reaction. Importantly, this type of inhibition is independent of the substrate concentration because the inhibitor does not directly compete with the substrate for the active site.

Step 3: Consider other inhibition types.
Un-competitive inhibition: Occurs when the inhibitor only binds to the enzyme-substrate complex, and its effect becomes more pronounced as substrate concentration increases.
Competitive inhibition: Happens when the inhibitor competes directly with the substrate for the active site, so the degree of inhibition is dependent on substrate concentration.
Mixed inhibition: Combines aspects of both competitive and un-competitive inhibition, with varying effects depending on binding affinities and substrate concentration.

Step 4: Conclusion.
Since the degree of inhibition in non-competitive inhibition does not depend on the substrate concentration, the correct answer is Non-competitive inhibition.