ENZYME ACTION

• Enzyme


  Biological protein catalyst
• Enzyme structure


  Tertiary structure creates shape of active site which substrate fits into to form enzyme-substrate complex
• Induced fit model


  Proximity of substrate leads to a change in the enzyme active- enzyme becomes flexible and can mould itself around the substrate and become completely complementary
• What causes bonds to break in substrate in induced fit model?


  As enzyme changes its shape its puts strain on the substrate molecule which distorts a bond/ bonds in the substrate therefore lowering the activation energy needed to break the bond
• What are the factors affecting enzyme action

  Temperature, pH, concentration
• How does increases temperature affect enzyme action?


  A rise in temperature increases the kinetic energy of the molecules resulting in them moving more rapidly, increasing the frequency of successful collisions- therefore more enzyme-substrate complexes are formed. Therefore rate increases.
• What happens when temperature gets too high?


  Enzyme denatures- active site changes shape due to strain in bonds- tertiary structure has changed.
• How does pH affect enzyme action?


  Each enzyme has an optimum pH at which it acts its fastest, if pH becomes extreme from the optimum it will become denatured.
• Why does extreme pH denature an enzyme?

  it can alter the amino acids making up the primary structure therefore affecting the bonds ultimately changing the active site so enzyme-substrate complex cannot be formed.
• How does concentration affect enzyme action?


  Increase in concentration of substrate or enzyme increases the rate until the other thing becomes the limiting factor as all substrate/enzyme will be taken up
• Competitive inhibitors


  Molecular shape similar to that of the substrate- fit into active site replacing substrate
• What effect does increased substrate concentration have on competitive inhibitor?

  Effect of inhibitor is reduced
• Does a competitive inhibitor permanently bind to the active site?


  No
• Non-competitive inhibitors


  Attach themselves to the enzyme at a separate binding site that changes the shape of the active site therefore making is no longer complementary to the substrate
• Does an increase in substrate concentration decrease the effect of the non competitive inhibitor? 


  No