Transcript Chymosin Lab

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
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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
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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
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7
8
9
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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
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b-galactosidase
H 2O
galactose
lactose
b-galactosidase
(aka lactase in humans)
glucose
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