Competitive inhibition

Definition

Competitive inhibition occurs when a molecule similar in structure to the substrate competes for binding to the active site of an enzyme. This prevents the substrate from binding and decreases the enzyme's activity.

5 Must Know Facts For Your Next Test

1. Competitive inhibitors increase the Km (Michaelis constant) of the enzyme but do not affect Vmax (maximum reaction rate).
2. The effect of a competitive inhibitor can be overcome by increasing substrate concentration.
3. Both the inhibitor and substrate compete for the same active site on the enzyme.
4. Competitive inhibition is often reversible, meaning that normal enzyme activity can be restored once the inhibitor is removed.
5. An example of competitive inhibition is the inhibition of succinate dehydrogenase by malonate.

Review Questions

• How does competitive inhibition affect Km and Vmax?
• Can competitive inhibition be overcome by increasing substrate concentration? Explain your answer.
• Provide an example of a competitive inhibitor and its corresponding enzyme.

Related terms

Non-competitive Inhibition: Non-competitive inhibition occurs when an inhibitor binds to an allosteric site on an enzyme, reducing its activity regardless of substrate concentration.

Active Site: The region on an enzyme where substrates bind and undergo a chemical reaction.

Allosteric Site: A site on an enzyme other than the active site where molecules can bind and influence enzyme activity.