Enzymes

• What are enzymes?

  • Tertiary proteins that act as biological catalysts
• How are enzymes biological catalysts?

  • They lower the activation energy of a reaction and speed up the rate of reaction
• What is the induced fit theory?

  • The active site of an enzyme undergoes a small conformational change to have a complimentary active site shape to the substrate shape
• How does pH affect enzyme rate of reaction?

  • The pH effects the charge of the amino acids, too high or low pH can break ionic and hydrogen bonds and alter the tertiary structure of the protein and denature the active site so it no longer form enzyme substrate complexes
• How does temperature effect enzyme rate of reaction?

  • Optimum temperature gives the enzyme more kinetic energy so there are more frequent successful collisions with substrate and form enzyme substrate complexes
  • Too low pH decreases kinetic energy so there are less frequent successful collisions
  • Too high pH may break bonds and alter the tertiary structure of the protein, denaturing the enzymes active site so it can no longer form enzyme substrate complexes
• How substrate concentration effect enzyme rate of reaction?

  • Increasing substrate increases the rate of reaction as there are more particles in the same volume, however once all the active sites are saturated the rate of reaction will remain constant as there is a different limiting factor
• How does enzyme concentration effect enzyme rate of reaction?

  • Increasing enzyme concentration increases the rate of reaction as there are more particles in the same volume and more active sites available so more enzyme substrate complexes can form
  • However, when substrate becomes the limiting factor, the graph will remain constant
• What is a competitive inhibitor?

  • A competitive inhibitors has a complimentary shape to the active site and occupies it, so the enzyme can no longer form enzyme substrate complexes with the substrate
• What is a non-competitive inhibitor?

  • The inhibitor attaches to the allosteric site of the enzyme, altering the active site so it is no longer complimentary to the substrate and can no longer form enzyme substrate complexes