information about enzymes

1. Enzymes

2. What is metabolism?
Sum of all chemical reactions in the body
Two Types:
1.Anabolism
2.Catabolism

3. 1. Anabolism
Small molecules chemically combing to
form a larger molecule
e.g. photosynthesis

4. 2. Catabolism
Large molecules broke down
into smaller molecules
e.g. respiration

5. Sources of energy
1.Solar energy
- Sunlight absorbed by pigments e.g. chlorophyll
2.Cellular energy
- Cell sources of energy capable of release by
metabolic reactions e.g. respiration

6. Definition of an enzyme
• Biological catalyst
• Speed up/ slow down the rate of chemical reactions without
being used up in the reaction
• 3D globular proteins
• Enzymes are the most important controllers of cellular
reactions

7. How enzymes work
• Enzymes are not flat they have a 3D
structure
• Each enzyme has its own specific shape
that will only ‘fit’ the molecule that the
enzyme is designed to work on

8. Enzyme action
• The substance that an enzyme works on
is its substrate
• The substance(s) that the enzyme forms
is called the product

10. Sample enzyme reaction
Substrate Enzyme Product
Starch Analyse Maltose
Lipids Lipase Glycerol +
Fatty acids
Proteins Pepsin Peptides

11. Optimum
temperature
• Human enzymes work best at
body temperature (37˚)
• Plant enzymes work best at
20-30˚
• Above certain temperatures
enzymes start to loose their
shape the rate of reaction falls
• When the shape is fully lost
the enzyme is said to be
denatured

12. To investigate the effect of
temperatures on catalase activity
1. Finely chop the celery. Weigh 5g of the chopped celery
2. Add 20ml of buffer pH9, on drop of washing up liquid and 5g of celery into
a graduated cylinder
3. Add 2ml of hydrogen peroxide to a boiling tube
4. Place the graduated cylinder and the boiling tube in an ice bath
5. Add the hydrogen peroxide into the graduated cylinder and record the
volume immediately
6. Time for 2 minutes and record the final volume
7. Repeat the steps for water baths at different temperatures

13. Results
Enzyme: catalase (source: liver)
Substrate: hydrogen peroxide (H2O2)
Product: 02 + water
How to measure rate: volume of foam produced in 2 min
Keep pH constant: buffer 9
Temperature 0˚ 20˚ 37˚ 60˚
Initial volume (ml) - - - -
Final volume (ml) 0 cm³ 5 cm³ 20 cm³ 0 cm³

14. To investigate the effect of pH on
catalase activity
1. Finely chop the liver. Weigh 3g
2. Add 10ml of buffer pH 4, one drop of washing up liquid and 3g of liver
into graduated cylinder
3. Add 2ml of hydrogen peroxide to a boiling tube
4. Place the graduated cylinder and the boiling tube in a water bath at
25˚
5. Add the hydrogen peroxide into the graduated cylinder and record
the volume immediately
6. Time for 2 minutes and record the final volume

15. Enzymes at work
Enzymes work best in certain conditions
Factors that affect enzymes include
o Temperature
o pH
o Substrate concentration
o Enzyme concentration

16. Optimum pH
• Enzymes work over a very
narrow pH
• Most enzymes work at pH 6-8
• Outside this they lose shape
and got denatured
• The best pH is usually 7
• Exception: pepsin is an
enzyme in the stomach that
works best at pH 2

17. Immobilised enzymes:
bio-processing
• The use of enzyme controlled reactions to produce
a product
• Bio-processing can be used to produce a vast
range of products such as cheeses, beer,
antibiotics

18. Immobilised enzymes:
bioproccessor/ bioreactor
VAT or Tank where enzymes work on
their substrates and turn them to
product

19. Immobilised enzymes:
immobilised enzymes
Are attached to each other or an inert
substance an can be used repeatedly

20. Advantages of immobilised enymes
• Easily recovered
• Pure sample
• Reused so cuts costs
• More stable

21. How to immobilise enzymes
Trapped in a gel sodium alginate is
commonly used this allows substrates in
and products out

22. Examples
Penicillin acylase changes the structure of penicillin to make more
antibiotics that will fight a wider range of bacteria
Immobilised enzyme: Penicillin acylase
Substrate: penicillin
Product: antibiotics

23. Two types of bioprocessing:
batch
All substrates are added in before the start of processing and discharged
at the end of processing
Advantages:
• Good for small quantities
• Not a lot of product lost if contamination occurs
Disadvantages:
• Time consuming
• More labour required

24. Two types of bioprocessing:
continuous flow
Substrate is simultaneously charged and discharged from the process
Advantages:
• Good for large quantities
• Less labour needed so lower cost
Disadvantages:
• Lots of products lost if contamination occurs
• High start up costs

25. Enzymes are specific:
induced fit theory
1. The substrate combines with the active site of an enzyme
2. The active site in induced or caused to change shape slightly
3. The substrate and enzyme form and enzyme substrate complex →
the bonds in the substrate are altered so that the substrate changes
into products
4. The products leave the active site. The active site returns to its
original shape and is ready for a new substrate molecules.

26. 1. To prepare one enzyme immobilisation
and 2. examine its application
1. In a beaker add 0.4g of sodium alginate to 10ml of distilled water and stir
2. In a separate beaker, add 2g of yeast to 10ml of distilled water and stir
3. In a separate large beaker, dissolve the calcium chloride in water
4. Add the yeast suspension to the alginate solution
5. Draw the liquid in a 20ml syringe
6. From a height of 10cm, release the mixture from the syringe into the
calcium chloride, one drop out at a time. Leave to harden for 10 minutes

27. 2. examine its application
1. Filter the hardened beads through a sieve and rinse with water
2. Mix 2g of yeast in 10ml of distilled water and pour into one of the separating funnels
3. Pour the beads into the second funnel
4. Dissolve 1g of sucrose in 100ml distilled water. Pour 50ml into each separating funnel
5. Immediately test the products in the beakers with glucose strips
6. Repeat test ever 2 minutes until glucose appears in both beakers
7. Remove off the remaining product from each funnel into the beakers and compare the
turbidity of the solution from both funnels

28. To investigate the effect of heat
denaturation on catalase activity
1. Put 5g of chopped liver into two boiling tubes in water baths at 100˚ and 20˚ for 10 minutes.
Remove and cool
2. Add 20ml of buffer pH9 to two graduated cylinders
3. Add one drop of washing up liquid to each cylinder
4. Add the 5g of chopped liver to one cylinder and label A. add the 5g of un-boiled liver to the
other cylinder and label B
5. Add 2ml of hydrogen peroxide to two new boiling tubes. Place both tubes in the water bath at
25˚
6. Stand cylinders and boiling tubes into the water until the desired temperature is reached
7. Add the hydrogen peroxide from each boiling tube to the corresponding graduated cyclinder

29. Expected results:
Not the presence or abstance of foam in each graduated
cylinder
Foam in B