ENZYMES


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  • ENZYMES
    • models
      • induced fit model
        • newer model, more realistic and used today
        • states that substrate interacts with bonds in tertiary structure of enzyme to make active site perfectly complimentary to substrate shape
      • lock and key model
        • old model, unrealistic and no longer used to explain ESC
        • states that the substrate has to have exact complementary shape to active site, this is fixed
    • role of enzymes
      • enzymes are biological catalysts and work by reducing the activation energy
        • activation energy is the energy needed to complete a reaction
        • anabolic - making up reaction
        • breaking down reaction
      • Vmax - maximum rate of reaction when the enzyme is fully saturated
      • extracellular enzymes which worl outside the cell... protease
      • intracellular enzymes which work inside the cell... catalyse/helicase
    • activation
      • co-factors, these are generally inorganic and temporarily
        • co-enzymes
          • type of cofactor that is organic (temporarily bound)
        • prosthetic groups
          • type of cofactor that is permanently bound (inorganic)
      • Organic - contain a carbon molecule
      • inorganic - doesn't contain carbon
    • factors affecting activity
      • temperature
        • increases kinetic energy which increases amount of successful collisions
        • when temperature increases past optimal level, hydrogen bonds break in tertiary structure permanently changing shape and preventing ESC forming
      • PH
        • hydrogen protons which determine PH interact with bonds holding together tertiary structure
        • when the PH is not optimal, being either too low or high, complimentary tertiary strutcure not correct
        • low PH (alkaline) - increase in protons
    • enzyme inhibition
      • competitive inhibition
        • involves inhibitor binding to active site of enzyme blocking complimentary substrate from forming the enzyme/subsrate complex
        • these are temporary - if enzyme concentration or substrate concentration is increased Vmax can still be reached, it will just take longer
      • non-competitve inhibitio
        • inhibitor binds to allosteric site changing the tertiary structure of enzyme and therefore shape of active site so ESP cannot form
        • Permanent change in structure, therefore Vmax may not be achievable

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