22.8 Using immobilises enzymes

Question 1

what are isolated enzymes?

Answer 1

enzymes outside of the organism

Question 2

why is using isolated enzymes wasteful?

Answer 2

enzymes are expensive to produced
they cannot be recovered as they are lost with the product

Question 3

what are immobilised enzymes?

Answer 3

enzymes which are attached to insoluble material to prevent them from mixing with the product

mimics how enzymes are attached to membranes in the body

Question 4

what are the advantages of immobilised enzymes?

Answer 4

cheaper
can be reused
can be separated from reactants and products easily
are more reliable
tolerant to higher temperatures
easily manipulated

Question 5

why is using immobilised enzymes cheaper?

Answer 5

no need for down-stream processing as enzymes can be easily re-obtained (no need to separate them out)

they can be reused

they are not as easily denatured

Question 6

why are immobilised enzymes more tolerant to high temperatures?

Answer 6

they are less easily denatured

can work at a wide range of temperatures

Question 7

what are the disadvantages of immobilised enzymes?

Answer 7

reduced efficiency

expensive
- higher initial cost of materials
- higher initial costs of bioreactor

extra equipment needed and complex methods used (something could go wrong)

Question 8

why are the initial cost of materials in immobilised enzymes higher?

Answer 8

immobilised enzymes are more expensive than free enzymes/microorganisms

Question 9

what are the ways that enzymes are immobilised?

Answer 9

adsorption
entrapment
covalent bonding

Question 10

adsorption description

Answer 10

enzymes bind to a surface by hydrophobic interactions and ionic links

enzyme being held is exposed to the substrate

Question 11

adsorption pros

Answer 11

simple and cheap

enzyme is very accessible to substrate

no effect on enzyme activity

Question 12

adsorption cons

Answer 12

bonding is not as strong which means that immobilised enzymes may detach

Question 13

covalent bonding description

Answer 13

enzyme binds using strong covalent bonds with inorganic carriers

these STRONG covalent bonds ensure enzymes remain fixed

Question 14

covalent bonding pros

Answer 14

enzyme is VERY STRONGLY held into place so will not be lost

enzyme is very accessible to substrate

pH and conc have little effect on enzyme activity

Question 15

covalent bonding cons

Answer 15

is expensive

active site may be modified during bonding
makes enzyme less effective —> reduces activity

Question 16

entrapment description

Answer 16

enzymes are trapped in a matrix which prevents them from moving

substrate must diffuse through to bind to enzyme

Question 17

cons of entrapment

Answer 17

expensive

difficult to entrap

diffusion of substrate can be too slow

Question 18

what are the main industrial uses of immobilised enzymes?

Answer 18

glucose isomerase
penicillin acylase
lactase
aminoacylase
glucoamylase
nitrile hydratase

Question 19

glucose isomerase

Answer 19

converts glucose to fructose

fructose used as sweetener in foods (more sweet than sucrose)

fructose also cheaper to produce than sucrose

Question 20

penicillin acylase

Answer 20

used to make semi-synthetic penicillins from natural penicillin

allows for mutated bacteria, who become penicillin resistant, to be treated with semi-synthetic penicillin

NEW MEDICINES to deal with resistant bacteria

Question 21

lactase

Answer 21

converts lactose into glucose and galactose

used to make lactose-free milk

Question 22

aminoacylase

Answer 22

used to produce L amino acids which are used for:
- pharmaceuticals
- organic chemicals
- additives in food

Question 23

glucoamylase

Answer 23

breaks down dextrins into glucose

dextrins are produced when starch is hydrolysed by amylase

Question 24

nitrile hydratase

Answer 24

converts nitriles to amides

acrylonitrile is hydrated to form acrylamide using nitrile hydratase

acrylamides are used in the production of plastics