Competitive and non-competitive inhibition

Overview

Term enzyme inhibitor, how a competitive inhibitor slows a reaction and effect of raising the substrate concentration on competitive inhibition.

What you need to know

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Questions from this subtopic

Each one with the model answer underneath.

1. 1

   Define the term enzyme inhibitor.

   Model answer

   An enzyme inhibitor is a substance that reduces or prevents the activity of an enzyme.

2. 2

   Where does a competitive inhibitor bind to an enzyme?

   Model answer

   A competitive inhibitor binds to the active site itself.

3. 3

   Why is a competitive inhibitor able to occupy an active site?

   Model answer

   Its molecular shape is similar to that of the substrate, so it fits the active site.

4. 4

   Explain how a competitive inhibitor slows a reaction.

   Model answer

   While it occupies an active site the substrate is excluded, so fewer enzyme–substrate complexes form per second.

5. 5

   What is the effect of raising the substrate concentration on competitive inhibition?

   Model answer

   The effect of the inhibitor is reduced, because substrate molecules are more likely to reach an active site first.

6. 6

   Can a reaction with a competitive inhibitor still reach its normal maximum rate?

   Model answer

   Yes, the maximum rate can still be reached provided the substrate concentration is raised high enough.

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