Enzymes

• Enzyme

  Biological catalysts that speeds up the rate of reaction

  By offering an alternative pathway with a lower activation energy
• Lock and key model

  Each substrate is a key that only fits a specific enzyme
• Induced-fit model

  A complementary substrate binds to an active site on an enzyme

  Enzyme changes shape slightly as substrate binds = forms an enzyme-substrate complex
• Active site

  A group of amino acids that makes up the region of an enzyme into which the substrate fits in order to catalyse a reaction - speed it up

  Its Shape is determined by the tertiary structure
• pH curve

  ...
• Temperature curve


  ...
• Enzyme concentration curve


  ...
• Substrate concentration curve


  ...
• Non-competitive inhibition

  Binds to the allosteric site of the enzyme

  Changes the tertiary structure of the active site

  Active site is no longer complementary in shape to the substrate

  Less enzyme-substrate complexes form

  Rate of reaction decreases

  Increase in substrate concentration won't return the rate of reaction back to normal
• Competitive inhibition

  Has the same shape as the substrate

  Complementary to the active site

  Binds to thee active site of enzyme temporarily

  Slows down the rate of reaction temporarily

  De-attaches and rate of reaction can return to normal

  Increase the concentration of substrates
• 5 factors that affect the rate of enzyme-controlled reactions?

  Enzyme/substrate concentration

  pH

  Temperature

  Concentration of inhibitors