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  • Enzymes
    • Basic
      • Globular proteins
      • Complementary to one substrate to form an enzyme-substrate complex
      • Lower the activation energy
    • Hypothesis
      • Induced fit
        • Enzyme and substrate not initially complementary
          • Enzyme moulds round substrate to form E-S complex
            • Distorts bonds in substrate and lowers AE
              • Products fall away from active site
                • Enzymes reverts back to original shape
      • Lock and key
        • Enzyme and substrate are complementary
          • Fit like a jigsaw to form E-S complex
            • Enzyme remains unchanged and product formed
    • pH
      • H+/OH- are attracted to the charges in polypeptide
        • Disrupt hydrogen and ionic bonds that maintain tertiary structure
    • Temperature
      • Molecules gain EK so more successful collisions
      • Atoms within enzyme also gain energy and vibrate
        • Hydrogen bonds that maintain tertiary structure break
          • Enzyme dentaured
    • Substrate/enzyme concentration
      • If one remains constant, rate will increase up to a point
        • Limiting factor
          • All enzymes are saturated in a given time
          • Not enough substrate to fill all active sites
    • Inhibitors
      • A substance which binds to an enzyme to stop or slow down rate of reaction
      • Competitive
        • Competes with substrate for active site
        • Substrate less likely to bind so fewer E-S complexes in a given time
        • Block active site
        • Increase rate again by increasing substrate concentration
      • Non-competive
        • Bind to allosteric site and alter shape of enzyme
        • Less enzymes available


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