Enzymes

Enzymes

Active sites and enzymes
1. Enzymes = globular proteins; biological catalysts
2. Substrates = substances enzymes convert into products
3. produced by living organisms
4. enzyme substrate specifity = must match
5. active site = special region on surface of enzyme that substrate binds to
6. only matching shapes can bind
7. once substrate converted to product, released
Enzyme activity
1. molecular motion; collision of sub. with act. site
2. stages
  1. sub. binds to act. site
  2. change into products
  3. products separate from site
3. most reactions, substrates dissolved in water
4. collisions due to random movement
5. successful only if aligned correctly
Factors affecting enzyme activity
1. Temperature
  1. Liquid temp increases, enzyme activity increases
  2. enzyme heated; denatures - zero activity
2. substrate concentration
  1. more substrate = more successful collision = more activity
  2. goes down after a point
3. pH
  1. acidity and alkalinity
  2. lower pH, higher H ion conc
  3. 1 unit = 10x acidity
  4. pH 7 neutral
  5. optimum pH = highest activity
  6. denatured when H ion conc too high/low
  7. wide range of optimum
Denaturation
1. structure permanently altered
2. unsuitable temperature or pH
Immobilised enzymes
1. widely used
2. discovered 1897 Buchner brothers
3. clearer falsification of vitalism
4. more than 500 commercial uses
5. limits enzyme movement
6. advantages
  1. can be removed easily; stop reaction and avoid contamination
  2. cost saving as recyclable
  3. increases stability and decreases degradation
  4. substrates can be exposed to higher enzyme conc. = higher reaction rates

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