Powerpoint enzymes models of action

Source: teachers.cie.org.uk

1. Enzyme Action
Enzymes: proteins that function as biological catalysts.
Catalyst: a substance that speeds up a chemical reaction and
is not changed by the reaction.

2. Lock and Key

3. Lock and Key
However certain substances can bind to the enzyme at sites other than the
Active site and modify its activity (inhibitors/co-factors)
Idea that the enzyme is flexible

4. Induced Fit

5. Enzyme reactions
enzyme + substrate enzyme-substrate complex

6. Enzyme reactions
enzyme + substrate enzyme-substrate complex
E +S ES

7. Enzyme reactions
enzyme + productenzyme-substrate complex
E +PES
enzyme + substrate enzyme-substrate complex
E +S ES

8. Enzyme activity
How fast an enzyme is working
Rate of Reaction

9. Enzyme activity
How fast an enzyme is working
Rate of Reaction
Rate of Reaction = Amount of substrate changed (or amount product formed)
in a given period of time.

10. Rate of Reaction
Enzyme activity
Variable you are looking at

11. Enzyme activity
Four Variables

12. Enzyme activity
Four Variables
Temperature
pH
Enzyme Concentration
Substrate Concentration

13. Rate of Reaction
Temperature

14. Rate of Reaction
Temperature
0 2030 5010 40 60

15. Rate of Reaction
Temperature
0 2030 5010 40 60
40
o
C - denatures
5- 40
o
C
Increase in Activity
<5
o
C - inactive

16. Effect of heat on enzyme activty
If you heat the protein above its optimal temperature
bonds break
meaning the protein loses it secondary and tertiary structure

17. Effect of heat on enzyme activty
Denaturing the protein

18. Effect of heat on enzyme activty
Denaturing the protein
ACTIVE SITE CHANGES SHAPE
SO SUBSTRATE NO LONGER FITS
Even if temperature lowered – enzyme can’t regain its correct shape

19. ph
•The ph scale measures how acidic or alkaline a
substance is.
•The chemical properties of many solutions
enable them to be divided into 3 categories:
1) Neutral: solutions with a ph of 7.
2) Alkaline: solutions with a ph greater than 7
3) Acidic: solutions with a ph less than 7.

20. Ph scale

21. Rate of Reaction
pH

22. Rate of Reaction
pH
1 342 56789

23. Rate of Reaction
pH
1 342 56789
Narrow pH optima

24. Rate of Reaction
pH
1 342 56789
Narrow pH optima
WHY?

25. Rate of Reaction
pH
1 342 56789
Narrow pH optima
Disrupt Ionic bonds - Structure
Effect charged residues at active
site

26. Rate of Reaction
Enzyme Concentration

27. Rate of Reaction
Enzyme Concentration
Enzyme Concentration

28. Rate of Reaction
Substrate Concentration

29. Rate of Reaction
Substrate Concentration
Substrate Concentration

30. Rate of Reaction
Substrate Concentration
Substrate Concentration
Active sites full- maximum turnover

31. Making use of enzymes
•Washing powders
•Food industry
•Germination of seeds
•Antibiotic penicillin

32. Washing powder

33. Biological washing powders
•Contain:
- lipase: greasy stains
- protease: eggs, blood
•Advantage: they work at lower
temperatures, so less water heating is
needed, and clothes don´t shrink.

34. Food industry
•Fruit juices: are extracted using pectinase. It
breaks down pectin and is much easier to
squeeze juice from the fruit. It also makes the
juice clear rather than cloudy.
•Biscuits: - isomerase: converts glucose to
fructose, which is sweeter so less needs to be
used in slimmers biscuits.
- protease: softens glutens, making
the roller of biscuits easier

35. Germination of seeds
•Amylase is found in seeds.
•When the seed begins to germinate, it
catalyses the break down of insoluble
starch to soluble maltose.
•The maltose is used by the growing
embryo : -as an energy source
- to make cellulose for new cell
walls.

36. We obtain many enzymes
from microorganisms
•Bacteria
•Microscopic fungi, such as yeast.
•They are grow inside fermenters.
•Conditions needed to grow and
reproduce:?

38. The fungus penicillium makes
penicillin
•The antibiotic penicillin is made by cultivating the
fungus in a fermenter.
•The fermenter is kept at the correct ph and
temperature for the enzymes of the fungus to
work well. What else do they need to grow?
•Its enzymes convert a substrate to a desired
product. Which one?
•First 15-24 hs. The fungus just grow.
•Then, it begins to secrete penicillin, which is
collected from the liquid part of the culture.