Competitive inhibitors

• What is the active site of an enzyme?


  A groove on the surface of an enzyme that is complementary to a specific substrate molecule
• What forms when a substrate binds to the active site of an enzyme?


  An enzyme-substrate complex
• What happens after the products are released from the active site?


  The enzyme can bind another substrate molecule and continue catalyzing the reaction
• What type of molecule can also bind to the active site besides the substrate?


  A competitive inhibitor
• What is the effect of a competitive inhibitor on the active site?


  It prevents the actual substrate from colliding with the active site
• What is an example of a competitive inhibitor mentioned in the video?


  Myelinate
• How does myelinate affect respiration?


  It inhibits respiration by preventing succinate from colliding with the active site of the enzyme
• How can the effect of a competitive inhibitor be reduced?


  By increasing the concentration of the substrate
• What happens to the rate of reaction as substrate concentration increases in the presence of a competitive inhibitor?


  The rate of reaction can eventually reach a maximum rate (v max) as more active sites are occupied by substrate
• What does v max represent in enzyme kinetics?


  The maximum rate of reaction when all active sites are occupied
• How does the presence of a competitive inhibitor affect the rate of reaction at a certain substrate concentration?


  It reduces the rate of reaction compared to the uninhibited enzyme
• What happens to the effect of a competitive inhibitor as substrate concentration increases?


  The effect of the competitive inhibitor reduces
• What is methotrexate used for?


  To treat certain cancers
• How does methotrexate function as a competitive inhibitor?


  It is a reversible competitive inhibitor of an enzyme found in human cells
• What is penicillin's role as a competitive inhibitor?


  It inhibits an enzyme involved in the synthesis of bacterial cell walls
• How does penicillin differ from methotrexate in terms of binding to enzymes?


  Penicillin binds irreversibly to the enzyme, while methotrexate binds reversibly
• What is the consequence of an irreversible competitive inhibitor binding to an active site?


  The effect cannot be reversed by increasing the substrate concentration
• What are the key points about competitive inhibitors?

  • Competitive inhibitors bind to the active site of enzymes.
  • They prevent substrate binding and reduce reaction rates.
  • Increasing substrate concentration can reduce their effect.
  • Some competitive inhibitors bind irreversibly, preventing any reversal of their effect.
• What is the relationship between substrate concentration and the rate of reaction in the presence of a competitive inhibitor?


  • As substrate concentration increases, the rate of reaction increases.
  • At high substrate concentrations, the effect of the competitive inhibitor diminishes.
  • The maximum rate (v max) is reached when all active sites are occupied.