Immobilised Enzymes in Biotechnology (OCR A Level Biology): Revision Note

Immobilised Enzymes in Biotechnology

• An immobilised enzyme is an enzyme that is attached to an insoluble material to prevent mixing with the product

• Enzymes can be immobilised in several ways:

  • Attached to an inert substance

  • Enclosed in a capsule

  • Contained within a partially permeable membrane

Different ways in which enzymes can be immobilised

• Enzymes are often immobilised for use in industrial processes as it means the enzyme can be reused in future processes rather than being discarded after it has been used once

• Reusing the enzyme also avoids the need to separate the enzyme from the product in downstream processing

  • The immobilised enzymes are contained within a column through which the substrate is filtered in solution

  • As the substrate runs through the column, enzyme-substrate complexes are formed and products are produced

  • These products then flow out of the column, leaving the enzymes behind to catalyse the reaction again

The immobilised enzymes are contained within a column

Advantages of immobilised enzymes

• There is no enzyme in the product (the product is uncontaminated) and therefore there is no need to further process or filter the end product

• The immobilised enzyme can be reused multiple times which is both efficient and cost-effective (enzymes are expensive)

• Immobilised enzymes have a greater tolerance of temperature and pH changes (immobilisation often makes enzymes more stable)

Disadvantages of immobilised enzymes

• Specialist expensive equipment is required

• Immobilised enzymes are more costly to buy, so are unlikely to be financially worthwhile for smaller industries

• The rate of reaction is sometimes lower when using immobilised enzymes as the enzymes cannot freely mix with the substrate

Immobilised enzymes in industry

• There are many industrial and medical applications of immobilised enzymes, including production of the following:

  • Lactose-free dairy products such as milk

    • Enzyme: Lactase

    • Converts lactose to glucose and galactose

  • Semi-synthetic penicillin which overcomes issues of penicillin resistance

    • Enzyme: Penicillin acylase

    • Converts the original form of penicillin into one which is effective against penicillin-resistant organisms

  • Glucose products used to sweeten and thicken foods

    • Enzyme: Glucoamylase

    • Converts starch and other dextrins into glucose

  • Fructose for sweetening of foods where a lower quantity of sugar is necessary

    • Enzyme: Glucose isomerase

    • Converts glucose into the sweeter sugar, fructose

  • Purified samples of L-amino acids used in food production

    • Enzyme: Aminoacylase

    • Separates out L-amino acids from D-amino acids

  • Acrylamide required in disposable nappy production

    • Enzyme: Nitrilase

    • Converts acrylonitrile into acrylamide

A closer look at lactose-free milk production

• Milk is a valuable source of nutrients containing protein, fat and the carbohydrate lactose

  • 5-10% of the UK population are lactose intolerant

  • Lactose is a disaccharide that is broken down into glucose and galactose

Using immobilised enzyme to modify milk