enzyme action

• Enzymes


  Tertiary structure proteins that catalyze different reactions
• Enzymes


  • Relatively large molecules compared to other biological molecules
  • Only a small part, the active site, is involved in catalyzing the reaction
• Active site


  Specific and unique shape where the complementary substrate binds to form the enzyme-substrate complex
• Tertiary structure of a protein


  Determined by the sequence of amino acids in the primary structure, which determines where bonds form and how the polypeptide chain folds
• Enzyme-substrate complex


  Forms when the substrate binds to the complementary active site of the enzyme
• Enzymes


  • Lower the activation energy required for a reaction to occur
• Enzyme catalysis (Lock and Key model)


  1. Enzyme and substrate collide and bind due to complementary shape

  2. Enzyme-substrate complex forms

  3. Substrate slightly distorts in shape, lowering activation energy

  4. Products are released, enzyme active site is empty and can be reused
• Enzyme catalysis (Induced Fit model)


  1. Enzyme active site is almost complementary to substrate

  2. Active site slightly changes shape to mold around the substrate

  3. Molding puts strain on substrate bonds, weakening them and lowering activation energy

  4. Products are released, enzyme active site returns to original shape and can be reused
• The Induced Fit model is the accepted model for how enzymes function