сofacto

• Enzymes

  • High specificity - they react with a specific type of molecule or closely related group of molecules
  • The molecule that reacts with the enzyme is called the substrate
  • The substrate binds to a specific location on the enzyme called the active site
  • The interaction between the enzyme and substrate is electric in nature
• Enzyme-substrate complex


  The complex formed when the enzyme binds with the substrate
• Co-actors


  Non-protein molecules that optimise the activity of enzymes
• Types of co-actors

  • Metal ions (inorganic co-actors)
  • Co-enzymes (organic co-actors)
• Co-substrates


  Co-enzymes that bind to the enzyme via loosely held bonds
• Prosthetic group


  Co-enzymes that bind tightly to the enzyme, usually via covalent bonds, and remain unchanged during the reaction
• Prosthetic group


  • Heme group
• Co-substrate


  • Coenzyme A
• Apoenzyme

  Enzyme without its co-actor
• Holoenzyme


  Enzyme with its co-actor bound
• Lock and key model


  Older model that states the active site is a perfect fit for the substrate, and neither the substrate nor enzyme change shape during binding
• Induced fit model


  Accepted model that states the active site is not a perfect fit, but both the enzyme and substrate change shape slightly to create a perfect fit
• Substrate binds to active site


  Enzyme and substrate change shape slightly to create a perfect fit (induced fit model)
• The induced fit model is the accepted model for how substrates bind to enzymes