Enzymes

Enzymes

1. Inhibitors

   • Competitive
     • They have a similar molecular shape to that of the substrate
     • Competes with the substrate for the active site
     • If substrate concentration increases it ill reduce the effect of the inhibitor
   • Non-Competitive
     • Binds to the enzyme (not the active site)
     • Alters the overall shape of the enzyme
     • Rate of reaction is unaffected by substrate concentration
     • Substrate will no longer fit in the active site

2. Medical and Industrial applications of enzymes

   • Immobilised enzymes
     • Immobilised Enzymes are enzyme molecules that are fixed, bound or trapped on a matrix such as a gel capsule (Algae Beads)
     • Advantages
       • can tolerate wider temperatures and pH
       • Does not get mixed up with the product
       • Enzymes can be easily recovered
       • Only a small amount of enzymes needed for a lot of products
   • Biosensors
     • Steps in using a Biosensor:
       • 1)Blood contains a mixture of different molecules
       • 2)Enzyme electrode is placed in a blood sample
       • 3)Glucose diffuses into the immobilised enzyme layer
       • 4)Oxygen is taken up
       • 5)The rate of Oxygen uptake is proportional to the glucose concentration
       • 6)A digital display shows an accurate concentration of glucose
     • The reaction produces a small electric current, which is picked up by the electrode

3. Enzyme Structure

   • Tertiary Globular Proteins
   • Catalyse metabolic reactions
   • Lock and Key theory
   • Induced fit theory
   • Catabolic reaction
     • 1 large molecule > Multiple small molecules
   • Anabolic reaction
     • Multiple small molecules> one large molecule
   • Bond
     • Hydrogen
     • ionic
     • Disulphide birdges

4. Factors affecting rate of reaction

   • Temperature
     • an increase in temperature causes greater kinetic energy in molecules. The molecules are moving around quicker meaning better chance of a successful collisions between the substrate an enzyme. This will continue until the optimum temperature has been reached (for most enzymes this is about 40*C). As the temperature increases above the optimum temperature the enzymes begin to denature due to the temperature breaking the hydrogen bonds. This alters the shape of the active site.
   • pH
     • extreme pH can cause the hydrogen bonds in the enzyme to weaken causing an alteration in the active site enzyme become denatured. Buffers maintain a constant pH. Buffers are used in experiments where the pH is needed to stay at a constant.
   • Substrate and enzyme concentration
     • • Substrate concentration- When substrate concentration increases the rate of reaction increases until a certain point where the enzymes will be saturated. • Enzyme concentration- increasing the enzyme concentration will increase the rate of reaction due to more active sites being available therefore more enzyme substrate complexes and more products.