Describe the reaction catalysed by lactase. Use Fig. 3.1 to help you. In your answer, identify R and product S.
On a commercial scale, immobilised lactase may be used to make lactose-free milk. One of the products in the reaction shown in Fig. 3.1 acts as an inhibitor of lactase. This is an example of product inhibition. Suggest why product inhibition is helpful in Kluyveromyces lactis when lactase is functioning as an intracellular enzyme, but may be a disadvantage when extracted lactase is used free in solution for the production of lactose-free milk.
Suggest how using immobilised lactase in a commercial process helps to reduce the issue of product inhibition.
The first large-scale production of lactose-free milk with an immobilised enzyme used lactase trapped in cellulose triacetate fibres. Suggest one property of cellulose triacetate that makes it useful as an immobilising material.
For a commercial application involving an enzyme, the progress of the enzyme-catalysed reaction must be examined. Outline how the progress of an enzyme-catalysed reaction can be investigated experimentally.