Immobilise enzymes

• These are enzymes that are fixed, bound or trapped in an inert matrix e.g alginate beadss.
• They can be packed into glass columns
• Substrate can be added to the top of the column and reacts with the enzyme as it slowly flows down.
• Once set up the column can be used again and again
• As the enzyme is fixed it doesn't mix up with the products therefore cheaper to seperate
• Immobilising enzymes creates micro environments allowing reactions to occur at higher temperatures than normal.

Other advantages

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  • Enzymes can tolerate wider range of conditions
  • Enzymes are easily recovered, reducing overall cost
  • Several enzymes with different optimal conditions can be used
  • Enzymes can easily be added or removed giving greater control of the reaction

• Biosensors work on principle that enzymes are specific and are able to select one type of molecule from a mixture.
• Can be used in the accurate detection of minute traces.
• Detection of blood sugar in diabetics
• The electrode probe has specific immobilised enzyme in a membrane and is placed in the blood sample.
• If glucose is present, it diffuse through the membrane and forms enzyme-substrate complex.
• This produces a small electric current which is picked up by the elecctrode which is read by the meter.
• Normal blood glucose levels are 3.89-5.83 mmol dm-3

Steps of using a biosensor:

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  • Blood contains a mixture of different molecules
  • Enzyme electrode is placed in a blood sample
  • Glucose diffuse through membrane enzyme layer
  • Oxygen is taken up
  • Rate of oxygen uptake is proportional to glucose concentration
  • Digital shows accurate concentration of glucose.