Factors affecting enzyme activity

• How does temperature affect enzyme activity?

  • Particles gain more kinetic energy so the substrate & enzyme can collide more frequently
  • After the optimum temperature is reached:
  • Bonds in the tertiary structure break & enzyme denatures
  • Enzyme active site changes shape, so fewer enzyme-substrate complexes are formed
• How does pH affect enzyme activity?

  • H+ or OH- ions disrupt ionic bonds in the enzyme's tertiary structure
  • The enzyme denatures & the active site changes shape
  • Fewer enzyme-substrate complexes are formed
• How can increasing enzyme or substrate concentration affect enzyme activity?

  • As 'x' concentration initially increases, enzyme activity also increases. When 'x's concentration increases, enzyme activity plateaus
  • All enzyme active sites may be occupied by a substrate so no more enzyme-substrate complexes are formed. Enzyme concentration = limiting factor
  • Or substrate concentration becomes the limiting factor
• What is a competitive inhibitor?

  A blocker that is similar to the substrate that binds to an enzyme's active site
• What is a non-competitive inhibitor?

  A blocker that binds to an enzyme's allosteric site, changing the shape of the enzyme & its active site
• What is a cofactor?

  Non-protein molecules that bind to enzymes to increase rate of reaction
• What are co-enzymes?

  Organic co-factors