Enzymes are proteins that act as biological catalysts, speeding up chemical reactions without being used up. They work via a "lock and key" mechanism, though the induced fit model suggests enzymes are flexible. Enzyme activity can be measured by looking at reaction rates under different temperatures, pH levels, enzyme and substrate concentrations. Heating an enzyme above its optimal temperature can cause it to denature, changing its shape so the active site no longer fits the substrate. Many enzymes are used industrially in washing powders, food processing, and antibiotic production.

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 + product enzyme-substrate complex E +P ES 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 20 30 50 10 40 60

15. Rate of Reaction Temperature 0 20 30 50 10 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 3 4 2 5 6 7 8 9

23. Rate of Reaction pH 1 3 4 2 5 6 7 8 9 Narrow pH optima

24. Rate of Reaction pH 1 3 4 2 5 6 7 8 9 Narrow pH optima WHY?

25. Rate of Reaction pH 1 3 4 2 5 6 7 8 9 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.