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Chymosin Lab

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Title: Chymosin Lab


1
Chymosin Lab
2
  • 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.

3
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)

4
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

5
ENZYMES
  • They are protein catalysts
  • They speed up reactions inside cells
  • They are incredibly specific
  • They are incredibly efficient
  • -ase enzyme

6
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

7
Enzymes make it easier for reactions to happen
8
Reactions can be exergonic, yet slow- they
require activation energy
9
Lowering the activation energy makes
enzyme-catalyzed reactions faster
10
THE REACTION DIAGRAM Enzymes can dramatically
lower the energy of activation for a reaction
no enzyme
with enzyme
E
a
E
Energy
a
reactants
products
Reaction Course
Note that the equilibrium of the reaction is
unaffected
12
11
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

12
Enzyme Inhibition- Enzymes can be sped up or
slowed down
13
Protease inhibitors make enticing HIV drug
candidates
14
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

15
Optimal temperature for typical human enzyme
Optimal temperature for enzyme of thermophilic
(heat-tolerant
bacteria)
Different enzymes work optimally at different pHs
and temper-atures
Rate of reaction
0
20
40
60
80
100
Temperature (C)
Optimal temperature for two enzymes
Optimal pH for pepsin (stomach enzyme)
Optimal pH for trypsin (intestinal enzyme)
Rate of reaction
0
1
2
3
4
5
6
7
8
9
10
pH
Optimal pH for two enzymes
16
  • 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.

17
b
-
galactosidase
10
18
b
-
galactosidase
H
O
2
galactose
lactose
b
-
galactosidase
glucose
(aka lactase in humans)
11
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