Using Immobilised Enzymes

Question 1

what are the advantages of using isolated enzymes instead of whole organisms?

Answer 1

• less wasteful
• more efficient ( isolated enymes work at much higher concentrations than is possible when they are part of the whole microoganism.
• more specific ( no unwanted enzymes are present so no wasteful side reactions take place. )
• maximise efficiency ( isolated enzymes can be given ideal conditions for maximum product formation which may differ from those needed for the growth of the whole organism.
• less downstream processing (pure product is produced by isolated enzymes. whole miroorganisms give a variety of products in the final broth, making isolation of the desired product more difficult and therefore expensive. )

Question 2

what are the different methods for immobilising enzymes?

Answer 2

• surface immobilisation (absorbtion to inorganic carriers)
• covalent or ionic bonding to inorganic carriers
• entrapment in a matrix.
• membrane entrapment in microcapsule.

Question 3

what are the advantages of absorption to inorganic carriers?

Answer 3

• simple and cheap to do.
• can be used with many different processes
• enzymes very acccessible to substrate and their activity is virtually unchanged.

Question 4

what is a disadvantage of absorption to inorganic carriers?

Answer 4

• enzymes can be lost from matrix relatively easily.

Question 5

what are the advantages of covalent or ionic bonding to inorganic carriers?

Answer 5

• cost varies
• enzymes strongly bound and therefore unlikely to be lost.
• enzymes very acessible to substrate.
• pH and substrate concentration often have little effect on enzyme activity.

Question 6

what are the disadvantages of covalent or ionic bonding to inorganic carriers?

Answer 6

• cost varies
• active site on the enzyme may be modified in the process, making it less effective.

Question 7

what are the advantages of entrapment in the matrix?

Answer 7

• widely applicable to different processes

Question 8

what are the disadvantages of entrapment in the matrix?

Answer 8

• may be expensive
• can be difficult to entrap
• diffusion of the substrate to and product from the activie site can slow and hold up the reaction
• effect of entrapment on enzyme activity very variable, depending on matrix.

Question 9

what are the advantages of membrane entrapment in microcapsules?

Answer 9

• relatively simple to do
• relatively small effect on enzyme
• widely applicable to different processes.

Question 10

what are the disadvantages of membrane entrapment in microcapsules?

Answer 10

• relatively expensive
• diffusion of the substrate to and product from the active site can be slow and hold u production.

Question 11

are most of the isolated enzymes used intracellular or extracellular?

Answer 11

extracellular

Question 12

why are extracellular enzymes used?

Answer 12

• they are secreted so easiet to isolate.
• microorganism produces relatively few extracllular enzymes so easier to identify and isolate required enzyme.
• extracellular enzymes tend to be more robust extracellular enzymes are adapted to cope with greater variations in temperature and pH than intracellular enzymes.