1.4 Immobilized enzymes

Question 1

How are enzymes immobilized?

Answer 1

When they are fixed, bound or trapped on an inert matrix such as sodium alginate beads or cellulose micro fibrils.

Question 2

Give examples of a inert matrix.

Answer 2

Sodium alginate beads or cellulose micro fibrils.

Question 3

Does an immobilized enzyme contaminate the product?

Answer 3

No - it is fixed.

Question 4

Why are immobilized enzymes useful in industry?

Answer 4

The enzyme can be recovered and reused, meaning
- this reduces costs
- it also means that only small amounts of an enzyme are needed
- the product is also not contaminated by the enzyme
- several enzymes can be used at once each acting on a specific substrate.

Question 5

Can lower/higher temperatures be used and have a higher yield than free enzymes?

Answer 5

Yes.

Question 6

What is an industrial example of an immobilised enzyme?

Answer 6

Lactase, which is used to produce lactose-free milk.

Question 7

What is lactase immobilised in?

Answer 7

Alginate gel beads.

Question 8

What can increase the rate of reaction?

Answer 8

Small beads as substrate molecules will have easier access to enzyme molecules, so higher rate.

Question 9

What are the advantages of immobilized enzymes?

Answer 9

• Increased stability and function over a wider range of temperature and pH than
  enzymes free in solution.
• Products are not contaminated with the enzyme.
• Enzymes are easily recovered for reuse.
• A sequence of columns can be used so several enzymes with differing pH or
  temperature optima can be used in one process.
• Enzymes can be easily added or removed, giving greater control over the
  reaction.

Question 10

What can enzymes be used for in medicine?

Answer 10

Biosensors or analytical reagents.

Question 11

What is an example of a biosensor?

Answer 11

Glucose oxidase electrode.

Question 12

How does the glucose oxidase electrode work?

Answer 12

• the enzyme glucose oxidase is immobilised in a gel
• a small sample of blood is passed over the enzyme
• when glucose in the blood comes into contact with the enzyme, a reaction occurs, which
  releases energy (chemical)
• the energy released is converted into electrical impulses
• the more energy released, the higher the concentration of glucose in the blood
• a digital display of accurate concentration is available by referring to reference data
  stored in the processing unit.