An enzyme is a protein that acts as a biological catalyst - it speeds up biological reactions without being changed or used up. Enzymes are folded into complex shapes that allow smaller molecules (substrates) to fit into their active site.
Immobilised enzymes are enzymes that are attached to an inert, insoluble material (eg. calcium alginate). Immobilised enzymes can be used to make lactose intolerant/cat milk through catalysing the breakdown of lactose to glucose and galactose.
- can catalyse the same reaction many times
- binding makes enzymes more stable and less likely to denature
- purification is not necessary
- requires extra time, equipment and work
- may be reduction in reaction time
- cannot be used if one of the substrates is insoluble