Enzyme Action & Specificity (Cambridge (CIE) O Level Biology): Revision Note

Enzyme Action & Specificity

• Enzymes are specific to one particular substrate(s) as the active site of the enzyme, where the substrate attaches, is a complementary shape to the substrate

• This is because the enzyme is a protein and has a specific 3D shape

  • Different types of enzymes have a different combination of amino acids in the protein, which results in a different shape

• This is known as the lock and key hypothesis

  • The active site is the lock and the substrate is the key 

  • Only specific shaped keys can fit into each lock

The lock and key model of enzyme action diagram

The lock and key model of enzyme action results in enzyme specificity