Lecture 21- enzyme application

Question 1

Can enzymic reactions be done without enzymes?

Answer 1

Yes as enzymes are ‘just’ catalysts
Reactions would happen without them but would be slower

Question 2

How to stop sucrose solutions crystallising

Answer 2

Problem at low temperature or high concentration
Use ‘invert’ sugar-converts some sucrose to glucose and fructose
Less crystallisation and fructose is sweeter than sucrose

Question 3

How to ‘invert’ sugar

Answer 3

Boiling- easy but energy expensive
Enzymatic- low temperature, no need for acid or subsequent neutralisation doesn’t risk burning or colouring sugar
Same end product but different circumstances require different approaches

Question 4

Enzyme optima

Answer 4

Enzymes have optimum temperature and pH

Question 5

Enzyme applications-medical

Answer 5

Specific therapeutic reactions required
Drugs- inhibitors or activators of enzymes

Question 6

Enzyme application- industral

Answer 6

Low temperature reactions
Complex relations on complex mixtures

Question 7

Enzyme application- laboratory

Answer 7

Detection reagents- some enzymes can produce light or create colour change. can amplify weak signals as each enzyme molecule converts multiple substrate molecules
Molecular biology-PCR- restriction enzymes cut DNA at specific sequences. DNA polymerases allow us to copy/amplify DNA

Question 8

Streptokinase enzyme

Answer 8

Clot-buster drug- cheap and effective
Phosphorylates plasminogen to give plasmin
Plasmin breaks down fibrin in blood clots
Releaves ischemia due to blood clots
Can induce immune response or allergy as it’s a foreign protein

Question 9

Rennet

Answer 9

Used in cheesemaking
Extracted from calves stomachs
Converts liquid milk to curds (solids) and whey
Mix of enzymes including chymosin/rennin
genetic modification of fungi allows production of vegetarian rennet

Question 10

Papain

Answer 10

Cysteine protease from papaya
Can tenderise meat by breaking down peptide bonds
Reduces toughness and stringiness in cheap meat

Question 11

Transglutaminase

Answer 11

‘Meat glue’
Bonds free amine groups to glutamines
Used commercially in imitation crab meat and fish balls
Can bond dissimilar ingredients together eg flourless noodles from fish/meat

Question 12

Biological washing detergents

Answer 12

Enzymes added to help remove stains (proteases, celluloses, amylases and lipases)
Mostly bacterial origin

Question 13

Enzyme inhibitors

Answer 13

Many drugs are enzyme inhibitors
Either reversible or irreversible

Question 14

Reversible enzyme inhibitor

Answer 14

May compete with substrate for active site or bind elsewhere to reduce function

Question 15

Irreversible enzyme inhibitors

Answer 15

Most covalently link yo enzyme, often in active site

Question 16

Examples of irreversible enzyme inhibitor

Answer 16

bind to bacterial transpeptidase
Stop cross-linking of cell wall peptidoglycan- cell wall is weak and bursts

Question 17

Clavulanic acid

Answer 17

Irreversible inhibitor
Enter beta-lactamase active site
Covalently bonds with serine within active site
Creates highly reactive cluvanic acid structure
Beta-lactamase is inactivated

Question 18

Augmentin

Answer 18

Two enzyme inhibitors working together
Combination of amoxicillin and clavulanic acid
Able to inhibit beta-lactamase activity so restores bacterial susceptibility to amoxicillin
Important for treating resistant infections