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Enzyme Action

18 th October. Enzyme Action. Learning objective : to describe different models for enzyme action and to investigate factors which control the rate of an enzyme reaction. Lock and Key. Active Site . YES ….this is an enzyme molecule --- VERY COMPLEX

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Enzyme Action

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  1. 18th October Enzyme Action Learning objective: to describe different models for enzyme action and to investigate factors which control the rate of an enzyme reaction

  2. Lock and Key Active Site

  3. YES ….this is an enzyme molecule --- VERY COMPLEX BUT …..it only is shaped for ONE SUBSTRATE enzyme animation

  4. Exceptions to 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

  5. Induced Fit

  6. Enzyme reactions enzyme + substrate enzyme-substrate complex

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

  8. Enzyme reactions enzyme + substrate enzyme-substrate complex E +S ES enzyme + product enzyme-substrate complex ES E +P Catabolic – breaking apart

  9. THERE ARE ALSO ENZYMES that BUILD substrates as well as take substrates apart as you have seen … Anabolic - building up / combining

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

  11. 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.

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

  13. Enzyme activity Four Variables

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

  15. Temperature Rate of Reaction

  16. Temperature Rate of Reaction 0 10 20 30 40 50 60

  17. Temperature 5- 40oC Increase in Activity 40oC - denatures Rate of Reaction 0 10 20 30 40 50 60 <5oC - inactive

  18. 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

  19. Effect of heat on enzyme activty Denaturing the protein

  20. 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

  21. pH Rate of Reaction

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

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

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

  25. pH Narrow pH optima Disrupt Ionic bonds - Structure Rate of Reaction Effect charged residues at active site 1 5 7 8 9 2 3 4 6

  26. Enzyme Concentration Rate of Reaction

  27. Enzyme Concentration Rate of Reaction Enzyme Concentration

  28. Substrate Concentration Rate of Reaction

  29. Substrate Concentration Rate of Reaction Substrate Concentration

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

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