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ENZYMES

ENZYMES. NAME: CHEBET MILTON CONTACT: miltonchebs2000@yahoo.com Subject: Biology Topic: Nutrition. Learning objectives. Define enzymes Classify enzymes Describe the mode of enzyme action (lock and key hypothesis) Do the mouse mischief exercises at the end using the given mice.

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ENZYMES

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  1. ENZYMES • NAME: CHEBET MILTON • CONTACT: miltonchebs2000@yahoo.com • Subject: Biology • Topic: Nutrition

  2. Learning objectives • Define enzymes • Classify enzymes • Describe the mode of enzyme action (lock and key hypothesis) • Do the mouse mischief exercises at the end using the given mice

  3. Introduction to Enzymes • What are enzymes biological catalysts, protein in nature which speed up and control the rate of chemical reaction in living organisms • Classification of enzymes • Intracellular enzymes. • Extracellular enzymes.

  4. Enzyme Action Learning objective: to describe different models for enzyme action and to investigate factors which control the rate of an enzyme reaction More free powerpoints at www.worldofteaching.com

  5. Lock and Key

  6. 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

  7. Induced Fit

  8. Enzyme reactions enzyme + substrate enzyme-substrate complex

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

  10. Enzyme reactions enzyme + substrate enzyme-substrate complex E +S ES enzyme + product enzyme-substrate complex ES E +P

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

  12. 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.

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

  14. Enzyme activity Four Variables

  15. Factors affecting Enzyme activity Temperature pH Four Variables Enzyme Concentration Substrate Concentration

  16. Temperature Rate of Reaction

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

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

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

  20. Effect of heat on enzyme activity Denaturing the protein

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

  22. pH Rate of Reaction

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

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

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

  26. 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

  27. Enzyme Concentration Rate of Reaction

  28. Enzyme Concentration Rate of Reaction Enzyme Concentration

  29. Substrate Concentration Rate of Reaction

  30. Substrate Concentration Rate of Reaction Substrate Concentration

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

  32. In this mischief exercise your are required to Highlight a word in the green (right hand) column and drag it into a middle box corresponding

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