1. Enzymes
Welcome to a new topic! Write down the enzyme names That you hear about in the presentation

2. Enzymes
Enzymes are proteins that act as biological catalysts
They lower the activation energy of a specific chemical reaction
Catalysts – speed up the chemical reaction and are not changed by the reaction
Lowering the activation energy has a profound effect on how rapidly the reaction is completed

3. What are enzymes? Enzymes are typically proteins Enzymes are specific
Enzymes act as catalysts to speed up the rate of reaction of a biological process
Enzymes are not used up by the reaction they catalyse
Enzymes were discovered by a German chemist called Eduard Buchner near the end of the nineteenth century. He discovered enzymes while trying to extract yeast fluid for medicinal use when he noticed that the sugar was continually being converted into alcohol. Even though Louis Pasteur had shown this about twenty years before Eduard Buchner, Louis Pasteur had said that it was the yeast itself that made the conversion.Eduard Buchner said that it was not the yeast but the ‘juice’ inside them. The word enzyme was used for the active ingredient in the yeast juice. Enzyme literally means ‘in yeast’ ( ‘en’ = in, ‘zyme’ = yeast) and all enzymes are used as organic catalysts to speed up chemical reactions in organisms.Without enzymes reactions in cells would be so slow that they would virtually not take place.

4. Enzymes: Vocabulary Check
Catalyst: A substance that speeds up a chemical reaction without itself being changed
Enzyme: A biological catalyst that is usually a protein
Substrate: The reactant(s) upon which an enzyme has its action
Product: A substance that results from a chemical reaction

5. Enzymes change substrates into products

6. Enzymes have active site (s)
An intricate pocket or cleft – a 3- dimensional entity – structurally tailored to accept a particular substrate Only fits its particular substrate

7. How do enzymes work? Substrate specificity Activation energy
Induced fit versus Lock and key mechanism
Another animated summary of how enzymes work

8. Enzymes Lower Activation Energy

9. What are the models used to describe enzyme action?

10. What are the models used to describe enzyme action?
Lock and key mechanism
Induced fit mechanism

11. The induced fit theory
The substrate plays a role in determining the final shape of the enzyme and that the enzyme is has some flexibility. This explains why certain compounds can bind to the enzyme but do not react because the enzyme has been distorted too much. Other molecules may be too small to induce the proper alignment and therefore cannot react. Only the proper substrate is capable of inducing the proper alignment of the active site
Induced fit in a moment....

12. Naming Enzymes (simplified classification)
Enzymes can be named according to the type of reaction that they catalyse
Carbohydrases
Lipases
Proteases
Enzymes can be named according to the substrate the interact with:
Maltase
Sucrase
Some enzymes just have individualised names:
Pepsin
Trypsin
Catalase

13. Key properties of enzymes
All enzymes are proteins
Enzymes are denatured (inactivated) by extreme temperatures
Enzymes work best at a particular temperature (which depends on the organism)
Enzymes work best at a particular pH (which depends on the organism)
Enzymes are catalysts (not degraded, ccan be used over and over again)
Enzymes are specific

14. Factors affecting Enzymes
Temperature pH
Substrate concentration
Enzyme concentration

15. The best way to understand temperature, pH and substrate concentration effects is through paying with this game.... and here's another....

16. Factors which affect enzyme activity 1: Temperature
From: GCSE Bitesize:

17. The effect of temperature
For most human enzymes the optimum temperature is about 37°C
Many are a lot lower. For example, cold water fish can die at 30°C since many of their enzymes denature
Many plant enzymes have optimal temperature of 28 – 30 C
A few bacteria in hot springs have enzymes that can withstand very high temperatures up to 100°C
Most enzymes are fully denatured at 70°C

18. Factors which affect enzyme activity 2: pH
Optimum pH values
Enzyme activity
Trypsin
Pepsin pH 1 3 5 7 9 11

19. The effect of pH The pH of a solution affects the shape of an enzyme
At non-ideal pH values, the active site is distorted and the substrate molecules will no longer fit
Extreme pH levels will produce denaturation
Many enzymes have pH values which are NOT neutral (pH = 7): e.g. pepson, trypsin in the stomach and gut

20. Denaturation
Denaturation is a change in the shape of an enzyme which prevents it from fulfilling its function. Enzymes (and other proteins) can be denatured by heat, pH changes, or certain chemicals NB: Denaturation is not the same as ‘killing’ – proteins and enzymes are not living things, so can’t be killed!

21. What does ‘enzyme denaturation’ mean?

22. Factors which affect enzyme activity 3: Substrate and enzyme concentration
From:
August 26th 2012

23. Substrate concentration: Enzymic reactions
Reaction velocity
Substrate concentration
Vmax

24. ‘Celebrity’ biological enzymes
Metabolic Enzymes ATP synthase Enzymes in digestion Amylase Pepsin Lactase

25. Metabolic enzyme: ATP synthase
‘one of the wnders of the molecular world’
ATP synthase is an enzyme, a molecular motor, an ion pump, and another molecular motor all wrapped together in one amazing nanoscale machine
ATP synthase in action

26. Amylase
all about amylase...
Amylase digestion (II)

27. Pepsin
All about pepsin
pepsin working in the stomach

28. Lactase
Got lactase?

29. Lactase