Immobilised enzymes and biosensors

Overview

Immobilised enzyme, three types of support material used to immobilise enzymes and how an enzyme is immobilised in an alginate gel.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   What is meant by an immobilised enzyme?

   Model answer

   An immobilised enzyme is one that has been physically or chemically secured on or inside an insoluble supporting material.

2. 2

   Name three types of support material used to immobilise enzymes.

   Model answer

   Enzymes are immobilised on fibres, in gels and on plastic beads.

3. 3

   Describe how an enzyme is immobilised in an alginate gel.

   Model answer

   The enzyme solution is mixed with sodium alginate and the mixture is dropped into calcium chloride solution, where each drop sets as a bead with the enzyme trapped inside.

4. 4

   Why is the activity of an immobilised enzyme usually lower than that of the free enzyme?

   Model answer

   Some active sites are hidden by the support material or face inwards, so substrate cannot reach them.

5. 5

   Give one way in which immobilisation makes an enzyme more stable.

   Model answer

   The support holds the tertiary structure in place, so the enzyme tolerates a wider range of temperature and pH before it is denatured.

6. 6

   Explain how immobilisation allows a continuous flow process.

   Model answer

   Substrate solution is passed steadily over the fixed enzyme, so product emerges continuously and the reaction never has to be stopped to recover the enzyme.

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.