Enzymes

Enzymes

Inhibitors
1. Competitive
  1. They have a similar molecular shape to that of the substrate
  2. Competes with the substrate for the active site
  3. If substrate concentration increases it ill reduce the effect of the inhibitor
2. Non-Competitive
  1. Binds to the enzyme (not the active site)
  2. Alters the overall shape of the enzyme
  3. Rate of reaction is unaffected by substrate concentration
  4. Substrate will no longer fit in the active site
Medical and Industrial applications of enzymes
1. Immobilised enzymes
  1. Immobilised Enzymes are enzyme molecules that are fixed, bound or trapped on a matrix such as a gel capsule (Algae Beads)
  2. Advantages
    1. can tolerate wider temperatures and pH
    2. Does not get mixed up with the product
    3. Enzymes can be easily recovered
    4. Only a small amount of enzymes needed for a lot of products
2. Biosensors
  1. Steps in using a Biosensor:
    1. 1)Blood contains a mixture of different molecules
    2. 2)Enzyme electrode is placed in a blood sample
    3. 3)Glucose diffuses into the immobilised enzyme layer
    4. 4)Oxygen is taken up
    5. 5)The rate of Oxygen uptake is proportional to the glucose concentration
    6. 6)A digital display shows an accurate concentration of glucose
  2. The reaction produces a small electric current, which is picked up by the electrode
Enzyme Structure
1. Tertiary Globular Proteins
2. Catalyse metabolic reactions
3. Lock and Key theory
4. Induced fit theory
5. Catabolic reaction
  1. 1 large molecule > Multiple small molecules
6. Anabolic reaction
  1. Multiple small molecules> one large molecule
7. Bond
  1. Hydrogen
  2. ionic
  3. Disulphide birdges
Factors affecting rate of reaction
1. Temperature
  1. 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.
2. pH
  1. 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.
3. Substrate and enzyme concentration
  1. • 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.

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