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Chymosin Lab 1. Which variables influence enzyme performance in general? 2. With these variables in mind, hypothesize: What are the optimal conditions for the performance of chymosin? (Hint: you might investigate the normal conditions under which substances like chymosin are active). 3. Briefly describe an investigation aimed at optimizing one variable in chymosin Performance. Milk contains casein • Casein- German, Kase= cheese • Casein is an emulsifying protein • It is also a storage protein • Structurally similar to gluten (found in grains) Cheese is made from curdled milk • Rennet is added from the 4th stomach of a calf • Rennet contains chymosin • Chymosin is an enzyme which cuts casein ENZYMES • They are protein catalysts • They speed up reactions inside cells • They are incredibly specific • They are incredibly efficient • -ase = “enzyme” Chymosin is a protease • A protease is an enzyme which cuts proteins • Specifically, it is an aspartate protease • Has an aspartate residue at its active site • HIV-Protease 1 is also an aspartate protease Enzymes make it easier for reactions to happen Reactions can be exergonic, yet slow- they require activation energy Lowering the activation energy makes enzyme-catalyzed reactions faster THE REACTION DIAGRAM Enzymes can dramatically lower the energy of activation for a reaction no enzyme with enzyme Ea Energy Ea reactants products Reaction Course Note that the equilibrium of the reaction is unaffected 12 The stages of enzyme catalysis • Substrate(s) binding • Reaction of substrate to form product(s) • Release of products • The enzyme is ready to bind the next substrate • Enzymes are unchanged by the reactions they catalyze Enzyme Inhibition- Enzymes can be sped up or slowed down Protease inhibitors make enticing HIV drug candidates Effects of Temperature and pH • Each enzyme has an optimal temperature in which it can function • Each enzyme has an optimal pH in which it can function • Tertiary structure can be radically altered by changes in pH Optimal temperature for typical human enzyme Different enzymes work optimally at different pHs and temperatures 0 Optimal temperature for enzyme of thermophilic (heat-tolerant bacteria) 40 60 Temperature (°C) 20 80 100 Optimal temperature for two enzymes Optimal pH for pepsin (stomach enzyme) 0 1 2 3 Optimal pH for trypsin (intestinal enzyme) 4 5 pH Optimal pH for two enzymes 6 7 8 9 10 1. Which variables influence enzyme performance in general? 2. With these variables in mind, hypothesize: What are the optimal conditions for the performance of chymosin? (Hint: you might investigate the normal conditions under which substances like chymosin are active). 3. Briefly describe an investigation aimed at optimizing one variable in chymosin Performance. b-galactosidase 10 b-galactosidase H 2O galactose lactose b-galactosidase (aka lactase in humans) glucose 11