Immobilised enzymes Flashcards
What are immobilised enzymes?
Enzymes that are fixed, trapped or bound on an inert matrix
What are some examples of how enzymes are immobilised?
Absorption onto an insoluble matrix
Covalent bonding to a solid support
Trapping within a gel
Encapsulation behind a selectively permeable membrane
Why do enzymes immobilised in beads have a lower rate of reaction than those immobilised on a membrane?
Some active sites are inside the beads and the substrate will take time to diffuse into them
Enzymes on a surface have active sites that are more available to the substrate so there is a higher reaction rate
What are some advantages of immobilised enzymes?
Enzymes are easily recovered for re-use
Product is not contaminated with the enzyme
Increased stability over a wider range of pH values
Increased stability over a range of temperatures and enzymes denature at higher temperatures
Several enzymes with differing temperatures or pH optima can be used in one process
Enzymes can be easily added or removed giving greater control over the rate of reaction
What does trapping enzyme do?
Stabilises it
Prevents the shape change that would denature its active site
It can be used under a wider range of conditions
How do immobilised enzymes help with lactose free milk?
Milk contains the sugar lactose
Some people are intolerant to this as they do not possess the enzyme lactase
Lactose-free milk can be produced using immobilised enzymes trapped in an alginate bead in a column to hydrolyse the lactose to its monosaccharides glucose and galactose
What are biosensors?
Convert a chemical signal into an electrical signal
Rapidly detect and measure very low concentrations of a specific substrate in a complex mixture
How do immobilised enzymes help with biosensors?
One particular use is the measurement of glucose concentration in blood samples
Enzyme glucose oxidase is immobilised on a selectively permeable membrane, when placed in the sample the enzyme binds to glucose
A small electric current is produced and detected by an electrode
Concentration of glucose can then be read on a screen
Name a medical condition that could be detected using a glucose biosensor
Diabetes
What does HFCS stand for?
High-fructose corn syrup
What is HFCS?
A sweetener manufactured in a multi-step process from starch
Involves several immobilised enzymes which require different conditions
What is the equation for high-fructose corn syrup?
Starch (alpha amylase / 90 degrees) –> oligosaccharides (glucoamylase / 60 degrees) –> glucose (glucose isomerase / stable up to 60 degrees) –> fructose
