Enzyme ihibitors

• Why is it important that reactions don't happen too fast in cells?

  To prevent the buildup of excess products
• How does controlling enzyme activity affect metabolic pathways?

  It regulates the rate and quantity of product formed
• What are inhibitors in the context of enzymes?

  Molecules that prevent enzymes from catalysis
• What is competitive inhibition?

  A molecule similar to substrate blocks the active site
• How does a competitive inhibitor affect the rate of reaction?

  It reduces the rate of reaction
• What factors influence the degree of inhibition by competitive inhibitors?

  Concentration of substrate, inhibitor, and enzyme
• Do most competitive inhibitors bind permanently to enzymes?

  No, they usually bind temporarily
• What happens to the Vmax in the presence of a competitive inhibitor?

  It does not change
• What occurs if substrate concentration is increased in the presence of a competitive inhibitor?

  More substrate can outcompete the inhibitor
• What is an example of a competitive inhibitor in cholesterol synthesis?

  Statins are competitive inhibitors
• What characterizes non-competitive inhibition?

  The inhibitor binds at an allosteric site
• How does non-competitive inhibition affect the enzyme's active site?

  It changes the shape, preventing substrate binding
• Can increasing substrate concentration overcome non-competitive inhibition?

  No, it cannot overcome the inhibition
• What are irreversible non-competitive inhibitors?

  Inhibitors that cannot be removed from enzymes
• What is an example of an irreversible non-competitive inhibitor?

  Organophosphates inhibit acetylcholinesterase
• What can result from the irreversible inhibition of acetylcholinesterase?

  It can lead to paralysis or death
• What is end-product inhibition?

  When the product acts as an inhibitor to its enzyme
• What is the purpose of end-product inhibition?

  To prevent excess product formation
• How does end-product inhibition serve as a control mechanism?

  It prevents waste of resources
• What is the role of phosphofructokinase in respiration?

  It catalyzes the addition of the second phosphate
• How is phosphofructokinase competitively inhibited?

  By ATP binding to the allosteric site
• What happens to respiration when ATP levels are high?

  Glucose isn't broken down efficiently
• What occurs as ATP is used up in relation to phosphofructokinase?

  Less ATP binds, allowing respiration to resume
• What are the types of enzyme inhibition?

  • Competitive inhibition
  • Non-competitive inhibition
  • End-product inhibition
• What is the significance of end-product inhibition in metabolic pathways?

  • Serves as a negative feedback mechanism
  • Prevents excess product formation
  • Conserves resources
• What are the effects of competitive and non-competitive inhibitors on enzyme activity?

  Competitive Inhibitors:

  • Reduce reaction rate
  • Can be overcome by increasing substrate concentration
  • Do not change Vmax

  
  

  Non-competitive Inhibitors:

  • Reduce reaction rate
  • Cannot be overcome by increasing substrate concentration
  • May be irreversible
• How does ATP regulate phosphofructokinase activity?

  • High ATP levels inhibit PFK
  • Low ATP levels allow PFK to function
  • Regulates glucose breakdown and ATP production