Transcript enzymes

ENZYME
CATALYSIS
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ENZYMES
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Globular Proteins
Active Site
One Substrate only
Induced Fit: Changes occur when
meet with substrate
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ENZYME CATALYSIS
Enzymes Catalysis - ↓ Activation
Energy - Faster Reaction without
change of form.
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Factors affecting change: pH,
temperature
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BEFORE THE LAB
Find out rate - enzyme catalasesubstrate → product
 Hydrogen peroxide = substrate
 amount of hydrogen peroxide
remain after reaction → titration
with KMnO4
 Titration - add KMnO - color
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change until target color
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LAB
1. Add 10ml of H₂O₂to each
of 7 beakers.
 2. Add 1ml of catalase to
the first beaker at 0
second.
 3. Observe the reaction
until the time labeled on
the beaker.
 4. Stop the reaction by
adding 10ml of H2SO4
 5. Repeat the process for
other remaining beakers.
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TITRATION
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1. Remove a 5ml sample for titration
and move the sample to a clean flask.
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2. Record initial burette reading.
3. Add
KMnO4
(purple) until faint brown
color persists (it is the endpoint of
process.)
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4. Record final burette reading.
5. Calculate the ml of
KMnO4
used to
reach the endpoint.
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6. Repeat the process for other remaining
beakers.
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* KMnO4 to the flask mix - lose color - all
peroxide reacted with
KMnO4 → additional
KMnO4 light brown or pinkish
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*
KMnO4 ↑ - peroxide ↑
We calculate the rate of a reaction by measuring or observing the
disappearance of substrate or the appearance of product.
This lab figured out the rate at which the enzyme catalase converts
substrate to product by observing the disappearance of substrate.
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Bibliography
1.LabBench
http://www.phschool.com/science/biology_place/labb
ench/lab2/active.html
2. Drug Strategies to Target HIV
http://www.chemistry.wustl.edu/~edudev/LabTu
torials/HIV/DrugStrategies.html
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