1. Enzymes

2. Characteristics All Enzymes are Proteins Catalysts – i.e. control the rate of a chemical reaction

3. How Enzymes work Enzymes bind and hold substrates (aka reactants) in a certain orientation to speed the chemical reaction along Enzymes change shape as they bind the substrates

4. the binding + substrates active site enzyme-substrate complex

5. the reaction, the release enzyme-substrate complex product

6. What about the other way? enzyme-substrate complex substrate enzyme product

7. Lactase 1926 aa’s long cell membranes - small intestines Lactase

8. Beano - alpha galactosidase breaks down trisaccharides raffinose – in beans, cabbage enzyme not in humans in bacteria in large intestines +

9. introducing activation energy net energy change activation energy –activation energy is the energy required to get a reaction going

10. How do Enzymes work? They lower the “activation energy” of the reaction net energy change –activation energy is the energy required to get a reaction going activation energy

11. Enzyme performance is affected by: – amount of substrate present –temperature –pH –Inhibitors –Poisons

12. Enzymes and Amount of Reactants  [ reactants ]  reaction rate because increased chance of finding molecules  [reactants]  reaction rate because decreased chance of finding molecules Experiment with amount and rate 1. Measure [S] or [P] 2. Combine and Plot

13. Enzymes and Temperature  temperature  reaction rate because increased kinetic energy breaks H-bonds  temperature  reaction rate because decreased kinetic energy does not break H-bonds

14. pH Acids – excess Hydrogen ions Bases – excess hydroxyl ions Neutral – equal numbers of H + and OH -

15. Enzymes and pH  pH changes reaction rate because H-bonds are altered  pH changes reaction rate because H-bonds are altered Experiment with pH and rate

16. Enzymes and pH each enzyme has an optimal pH; some work best in acidic conditions (<4) (pepsin) while others work best closer to a neutral pH (7) pH for Optimum Activity Enzyme pH Optimum Lipase (pancreas) 8.0 Lipase (stomach) 4.0 - 5.0 Lipase (castor oil) 4.7 Pepsin 1.5 - 1.6 Trypsin 7.8 - 8.7 Urease 7.0 Invertase 4.5 Maltase 6.1 - 6.8 Amylase (pancreas) 6.7 - 7.0 Amylase (malt) 4.6 - 5.2 Catalase 7.0

17. Enzymes and Inhibitors

18. bind to specific enzymes and decrease the reaction rate Normal substrate enzyme binding Competitive inhibitor binds to the active site Noncompetitive inhibitor binds to the enzyme and changes its shape

19. Competitive Inhibitors

20. Noncompetitive Inhibitors

21. Poisons - KCN Specific Irreversible Inhibitor of Cytochrome C Oxidase, ATP cannot be made Anaerobic respiration only Fatal build up - Lactic Acid

22. Poisons - Arsenic Nonspecific Inhibitor of cellular respiration enzymes Inhibits glucose break down Cell death results