Immobilised enzymes Flashcards
What is meant by the term immobilised enzyme?
It is when enzyme molecules are fixed, bound or trapped to an inert matrix over which the substrate molecules move.
What does trapping an enzyme molecule do to its shape?
It prevents it from changing shape, because in a solution high temperatures and pH would denature the enzyme. Trapping the enzymes allows them to be used in a wider range of conditions.
Why do enzymes immobilised in beads have a lower rate of reaction than immobilised enzymes in a membrane?
Some active sites are inside the beads which means it takes the substrate time to diffuse to them whereas enzymes on a membrane are readily available for binding giving a higher rate of reaction.
What are the advantages of immobilised enzymes?
The polymer matrix creates a micro environment in the area so there is an increase in stability and so can function over a wider range of conditions and enzymes free in solution
Products are not contaminated with the enzyme
Enzymes can be easily recovered for reuse
A sequence of columns can be used so several enzymes with differing pH and temperature optimum and can be used in one process
Enzymes can be added or removed giving greater control over the reaction
What are the disadvantages of immobilised enzymes?
In absorption an enzyme may become detached.
If enzymes are held within a substance that takes time for the substrate to diffuse out of the gel.
The presence of gel alters the shape of the active site reducing activity compared to a free enzyme.
Chemical bonding in the enzyme is complex and expensive.
Any contamination is costly as the whole system would need to be shut and re-sterilised.
What are the methods of a immobilising enzymes?
Carrier- bound enzyme, entrapment, in-capsulation in alginate beads and chemically bonded cross links with glutaraldehyde.
Why are immobilised enzymes used in lactose free milk?
The milk is passed down the column which contains the immobilised enzyme lactase. The lactose binds to its active site and is hydrolysed into its components glucose and galactose.
What are biosensors?
They convert chemical signals into electrical signals which rapidly in accurate need to text identify and measure important molecules even at low concentrations.
How is biosensors use in detecting blood glucose levels?
It allows them to detect glucose levels in the blood as the enzyme glucose oxidase is immobilised on a selectively permeable membrane place in the blood sample that binds to glucose. This produces a small electric current detected by the electrode read on the screen
What are the roles of the biosensor?
The bio-receptor : the immobilised enzyme binds to the specific molecule been detected by the biosensor.
The transducer: convert products change into an electrical signal.
Amplifier: magnifier strength of an electrical signal so can be measured by meter.
Why is high fructose corn syrup manufactured using immobilised enzymes?
They are manufactured from the multistep process from starch where it uses several immobilised enzymes as each step uses different physical conditions.
