Immobilised enzymes Flashcards
What are immobilised enzymes?
Enzymes used in industrial processes, that are attached to an inert support material, and over which a substrate passes
What are the main pros of immobilised enzymes compared to whole organisms?
- More efficient
- More specific (can optimise conditions for a particular enzyme)
- Immobilised enzymes do not need food or oxygen
What are the main pros of immobilised enzymes compared to free enzymes?
- Can be removed to be reused
- More easily separated from products to give a purer product and less downstream processing
- Greater temperature tolerance to give faster rate
- More reliable as a greater level of control over the process
What are the main cons of immobilised enzymes compared to free enzymes?
- Immobilising an enzyme may reduce its activity rate
- Higher initial costs of materials
- More complex reactor needed for immobilised enzymes; more expensive and more possible technical issues
What is the main pro of whole organisms compared to immobilised enzymes?
Avoids the time-consuming and expensive process of extracting enzymes and immobilising them
What are the two different groups that methods of immobilisation can be separated into?
- Surface immobilisation
- Entrapment
What are the two different methods of surface immobilisation?
- ADsorption
- Covalent or ionic bonding to an inorganic carrier
What is the difference between adsorption and covalent/ionic bonding to an inorganic carrier?
Adsorption uses relatively weak bonds to stick the enzyme to the carrier, whereas alternatively very strong ionic or covalent bonds form between the enzyme and carrier
What are the advantages and disadvantages of ionic/covalent surface immobilisation compared to adsorption?
More tightly bound so:
- Less likely to be lost (pro)
- Less flexible so less efficient (con)
What are the two different methods of entrapment?
- Entrapment in a matrix
- Entrapment in microcapsules or semi-permeable membrane
What are the advantages and disadvantages of entrapment compared to surface immobilisation?
- More protected so less likely to be lost (pro)
- Material to make them is more expensive (con)
- Efficiency is lower as substrates have to diffuse in (con)
Example of suitable carrier that enzyme can form covalent bond with
Collagen
Example of suitable carrier that enzyme can form ionic bond with
Clay
Example of suitable matrix that enzymes can be entrapped in
Cellulose network
Example of a suitable microcapsue that enzymes can be entrapped in
Aliginate beads
