Enzymes

Enzymes

1. An enzyme is a protein catalysts that speeds up a reaction without being used up in the reaction

2. Active site Theory of Enzyme Action

   • The active site of an enzyme is the area where the substrate enters and is changed into a product
   • Specificity refers to an enzyme's ability to react with only one substrate
   • The lock and key model
     • Enzyme has a rigid shape and substrate fits into active site
   • The Induced fit Model
     • The substrate(s) does not fit perfectly into active site but the active site is flexible
       • Active site changes shape to fit substrate, enzymes active site acts on substrate to convert it to a product
         • Product is released and active site changes back to its original shape

3. Factors affecting Enzyme Action

   • Temperature
     • Above a certain temp. the enzyme loses its shape and its ability to function. It is said to be denatured
     • As the temp. rises, molecules move faster. This causes enzymes and substrate molecules to collide more often. For this reason the rate of enzyme reaction increases with temp.
     • It's optimum temperature 37 ºC
   • pH
     • Changes in pH disrupt the enzyme's shape
       • If the enzyme's shape is lost, it cannot act on its substrate

4. Bioprocessing

   • is the use of enzyme-controlled reactions to make a product
   • Immobilised Enzymes
     • are enzymes that are attached to each other or to an inert substance
     • Benefits
       • Immobilised enzymes can be reused
       • Product contains no enzyme (saves on separation costs)
       • They are as efficient as isolated enzymes
     • Uses
       • Immobilised lactose breaks down lactose in milk for lactose-tolerant people
       • Immobilised glucose isomerase is used in sweet manufacture to convert glucose to fructose
   • A bioreactor is a vessel in which cells or enzymes produce useful products

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