Enzyme Inhibitors + Immoblised Enzymes Flashcards
What are inhibitors?
Enzyme inhibitors can inhibit function of an enzymes
What is competitive inhibition?
Where the inhibitor has a a similar shape to the substrate, complementary to the active site so it fits into it, meaning the substrate can no longer.
This means it competes with the substrate for the active site
- id there is more substrate than inhibitor, effects of inhibitor are reduces
Inhibitors may fit permanently into active site (irreversible)
May fit temporarily into active duty (reversible)
Graph on notes
What is non-competitive inhibition?
The inhibitor fits into an area called the allosteric site, not active site
This changes the shape of the active site so it is no longer complementary to substrate, so substrate does not bind.
It does not compete for active site
May fit irreversibly or reversibly
- many are irreversible like potassium cyanide which inhibits enzyme involved in aerobic respiration, so ATP is not produced so death.
- many toxins produced by animals and plants are enzyme inhibitors for self Defense/killing etc
Graph on notes
What is feedback inhibition?
Chemical reactions which take place in our cells make up our metabolism.
Each reaction is carried out with different enzymes
If there are a series of reactions, end product my act as inhibitor to the earlier enzymes, slowing down the quantity of product.
This is feedback inhibition
This is a way of regulating the concentration/quantity of the product in the body
Diagram in notes
What are immobilised enzymes?
Enzymes are immobilised when they are fixed, bound or trapped on an inert matrix such as sodium alginate beads or cellulose microfibrils packed into columns.
What are industrial enzymes?
Enzymes produced by culturing microbes in a fermentation vessel, which produces enzymes as usual metabolic activity
Microbes killed and enzymes extracted and purified
Enzymes then used to catalyse reactions which usually require lots of energy
What are the advantages of using immobilised enzymes?
- enzymes are easily recovered, so can be used again and again, reducing costs
- product not contaminated by enzyme
- polymer matrix creates micro environment for enzyme so it is more stable at extreme temps and ph’s
- can be used in continuous processes, product of one reaction can be used as substrate as another, catalysed by different reaction
- several enzymes with different optima’s can be used at same time
What are the disadvantages of immobilised enzymes?
- in adsorption, enzyme may detach
- if enzymes are held in a substance e.g. alginate gel, it must diffuse, which takes time, free enzymes can reach substrate instantly, so lower ROR
- alginate gel changes active site, reducing activity
- chemically bonding the enzyme is complex and expensive
- any contamination means entire system has to be shut down
How do immobilised enzymes work in a reactor vessel?
- The substrate e.g. maltose are trickled down the vessel through the top.
- reaction occurs as substrate passes through immobilised enzymes
- products e.g. glucose collected from bottom
What are the 3 methods of immobilising enzymes?
- carrier-bound enzymes where attached to glass beads, collagen etc
- entrapment in cellulose mesh/alginate beads
- chemically bonded
What are biosensors?
An instrument that can detect a specific molecule in a mixture of molecules by turning a biochemical signal into an electrical one
How do biosensors work?
They rapidly and accurately detect, identify and measure even very low concentrations of molecules.
They work as enzymes are specific so only select one type of molecule from mixture.
One use is testing blood-glucose concentration, enzyme glucose-oxidase in selectively permeable membrane placed in blood sample, binds glucose, producing a small electric current detected by electrode and red on screen.
Can also be immobilised in test strips, can be used for detecting glucose in urine
