Enzyme immobilisation
Enzyme molecules bound to an inert (not active) material, over which the substrate molecules move
Benefits of immobilising enzymes
Columns can be used repeatedly, enzyme is fixed so cannot contaminate product, easy to purify product and makes enzymes more stable as it creates microenviroments which allow reactions to occur at higher temperatures or more extreme pH than normal
Why do immobilised enzymes on beads have a lower rate of reaction than those immobilised on a membrane
Active sites can be hidden amongst the beads/substrate takes a while to diffuse to them
Biosensor
Device which turns a chemical signal into an electrical signal. They rapidly and accurately detect concentrations of important molecules, working on the principle that enzymes are specific and are able to select one type of molecule from a mixture
Glucose oxidase
Immobilised on a selectively permeable membrane. When placed in a blood sample, glucose oxidase oxidises glucose producing hydrogen peroxide. This is detected by an electrode and the electrode then converts this into an electrical signal which is read by the device.
Glucose test strips
Work by placing a blood/urine sample on the strip. The strip contains immobilised glucose oxidase and the glucose in the blood reacts with the enzyme, producing gluconic acid. The varying amount of acid produces indicates level of glucose