Enzymatics

1. Enzymatics

2. 5.1 Enzymatic Activity Enzymes are proteins with tertiary or quaternary structures Each one has a unique 3D configuration that is a product of its unique sequence of amino acids Molecules that react with enzymes are called substrates Ex. Maltose is substrate for maltase, and sucrose for sucrase

3. Catabolism is when an enzyme reaction involves the cleaving of a single substrate into two products Anabolism is the opposite reaction Homeostasis is the process of keeping the internal environment constant

4. Lock and Key Analogy

5. The activated enzyme-substrate complex is when the substrate and enzyme are attached It is believed that when the activated ES forms, it forces the substrate into a slightly different shape. Scientists refer to this as the induced fit hypothesis The reaction proceeds when the required energy exists

6. The portion of the enzyme that attaches to the substrate is called the active site If an ES complex cannot form then no reaction takes place It is possible for a substance to fit into an active site, with no reaction occurring because the configuration of the combination is not correct (inhibited)

7. The amount of ATP required for a reaction is called the activation energy Enzymes lower the activation energy for a specific reaction

8. If the overall reaction results a net input of energy, it is termed endothermic If the overall reaction results in a net output of energy, it is termed exothermic Many enzymatic reactions exist as part of a larger metabolic pathway,where the product of one step becomes the substrate for a subsequent reaction

9. When enough of an end product is formed, the product begins to inhibit an enzyme from earlier on to stop the continual forming of itself. This process is called negative feedback Some reactions need the help of co-enzymes and cofactors to create the correct shape of the enzyme substrate

10. Review • Which of the following is FALSE about enzymatic reactions? a) Enzymes can be used repeatedly b) The energy of activation required for a reaction is increased by the presence of enzymes c) Substrates temporarily bond onto enzymes for a reaction to occur d) Enzymes each catalyze only one specific reaction

11. Which of the following is FALSE about enzymatic reactions? a) Enzymes can be used repeatedly b) The energy of activation required for a reaction is increased by the presence of enzymes c) Substrates temporarily bond onto enzymes for a reaction to occur d) Enzymes each catalyze only one specific reaction

12. Where does the energy for enzymatic reactions come from? a) ATP b) Enzymes c) Substrates d) Co-enzymes

13. Where does the energy for enzymatic reactions come from? a) ATP b) Enzymes c) Substrates d) Co-enzymes

14. Which of the following is TRUE about a metabolic pathway a) ATP is required at each step b) A final end product is never produced c) The same enzyme is used each step in the pathway d) the products become the next substrates

15. Which of the following is TRUE about a metabolic pathway a) A net loss of ATP is required at each step b) A final end product is never produced c) The same enzyme is used each step in the pathway d) the products become the next substrates

16. Which part of a persons diet supplies them with co-enzymes? a) Lipids b) Proteins c) Vitamins d) Carbohydrates

17. Which part of a persons diet supplies them with co-enzymes? a) Lipids b) Proteins c) Vitamins d) Carbohydrates

18. Which part of a persons diet supplies them with co-factors? Fats Water Minerals Vitamins

19. Which part of a persons diet supplies them with co-factors? Fats Water Minerals Vitamins

20. Factors Affecting Enzymes Temperature pH Heavy Metal ions Inhibitors Substrate and enzyme concentration

21. 5.2 Temperature H-bonds that help maintain the tertiary structure of enzymes are sensitive to temperature Too much exposure to a temperature increase will cause the bonds to break (denature) and the enzyme to take a new set of properties

22. The optimumtemperature of an enzyme is the temperature when the shape of the active site most exactly matches the shape of the substrate In humans, this temperature is about 37o C

23. As body temperature increases, human enzymes continue to function at a decreasing rate up to about 50o C before they denature At temperatures less than 37o C, reactions slow because of decreased kinetic energy This event is called hypothermia

24. Some victims of hypothermia drop 15-20o C and have been revived Brain damage often occurs if the body temperature is very low for very long, but the enzymes required for life can become renatured

25. 5.3 pH As with temperature, an enzyme functions best at an optimumpH Deviations from this pH can result in the denaturing of the enzyme Such is the case with the digestive system

26. Stomach enzymes function at a pH of about 2.5 The enzymes of the small intestine function better at a pH of 8.3 The body has a mechanism for adjusting the pH between these organs

28. If the pH of blood were to deviate very far from its average pH of between 7.3 and 7.4, death would be imminent

29. Review A particular reaction that occurs in the mouth was proceeding in a test tube at 45oC and at a pH of 2.5. Which of the following would likely cause the greatest INCREASE in the reaction rate? Raise the temperature and increase the pH Raise the temperature and decrease the pH lower the temperature and decrease the pH lower the temperature and increase the pH

30. A particular reaction that occurs in the mouth was proceeding in a test tube at 45oC and at a pH of 2.5. Which of the following would likely cause the greatest INCREASE in the reaction rate? Raise the temperature and increase the pH Raise the temperature and decrease the pH lower the temperature and decrease the pH lower the temperature and increase the pH

31. Which component is temperature and pH sensitive? E S P None of them are

32. Which component is temperature and pH sensitive? E S P None of them are

33. 5.4 Heavy Metals When heavy metal ions (like Hg2+ and Pb4+) get together with enzymes, they tend to disrupt the normal distribution of electrons in the enzyme When this happens, the shape of the enzyme is affected, lessening the chance of forming the activated ES complex

34. 5.5 Inhibitors • The presence of inhibitors affects the ability of an enzyme to bond with its substrate • Two types: • Competitive Inhibitors • Non-competitive Inhibitors

35. Competitive Inhibitors Compete with the substrate for occupancy of the active site The greater the concentration of the inhibitors relative to the concentration of the substances, the more of an effect on the rate of enzyme activity As long as the inhibitor is occupying the site, no ES forms

36. Non-competitive Inhibitors Combine with the enzyme in a location other than the active site and affects its shape, preventing the formation of the ES complex

37. 5.6 Substrate and Enzyme Concentrations Reaction rate increases as substrate concentration increases until all of the enzymes are in use At this point the rate of reactions is constant

38. Review Which of the following factors will NOT denature an enzyme? pH Temperature Concentration Heavy Metals

39. Which of the following factors will NOT denature an enzyme? pH Temperature Concentration Heavy Metals

40. Which of the following is the LEAST likely to affect the rate of enzymatic activity? pH Temperature Concentration Osmotic Pressure

41. Which of the following is the LEAST likely to affect the rate of enzymatic activity? pH Temperature Concentration Osmotic Pressure

42. Generally increasing the enzyme concentration in an enzymatic reaction will cause the reaction to Stop Reverse Speed up Slow down

43. Generally increasing the enzyme concentration in an enzymatic reaction will cause the reaction to Stop Reverse Speed up Slow down