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Non-competitive inhibition

This occurs when:

  • an inhibitor does not bind to the active site but binds to a different part of the enzyme
  • this changes the active site shape
  • this stops the substrate binding to the enzyme and decreases the reaction rate
Substrate can’t bind because competitive inhibitor prevents it accessing active site.  Non-competitive inhibitor embedded in bottom of enzyme. Active site altered so substrate still can’t bind.

Non-competitive inhibition cannot be reversed by increasing the substrate concentration.

Examples of non-competitive inhibitors include cyanide, mercury and silver.