Transcript document

The Effect of Amylase Concentration and pH
Levels on Time of Starch Disappearance
Carboxypeptidase (1)
With an Additional
focus on
Carboxypeptidase
Amylase
By: Pauline Hickey, Amanda Clark,
Peter Crane, Anya Novikova
Results Section
The Effect of Enzyme Concentration
on the Rate of Starch Digestion
Time of Starch Disappearance (in seconds)
250
223.6
200
150
Our Results
100
Class Average Results
Our Results Table
Percent
Concentration
of Amylase
Time of Starch
Disappearance
(in seconds)
0.5
10
0.25
20
0.125
50
0.075
60
81.6
60
50
50
53.6
Class Average Results Table
20
16.6
10
0
0
0.1
0.2
0.3
0.4
0.5
0.6
Percent Concentration of Amylase
• In both scatter plots, the time required to
digest starch decreased as the
concentration of amylase increased.
• Both data bases (our/class) show that
there was an inverse relationship
between the two variables.
Percent
Concentration
of Amylase
Time of Starch
Disappearance
(in seconds)
0.5
16.6
0.25
53.6
0.125
81.6
0.075
223.6
Our Results Table
The Effect of Different pH Values on
the Rate of Digestion
The pH
Time of Starch
Disappearance
(in minutes)
2
9
Time of Starch Disappearance (in minutes)
10
9
9
9
9
8
8
7
Our
Results
4
5
6
Class
Average
Results
6.8
0.5
8
2
10
9
5
5
5
4
3
2
2
1.83
Class Average Results Table
1
0.47
0.5
The pH
Time of Starch
Disappearance
(in minutes)
• Both graphs show that more time was needed
2
9
to digest starch at the highest and lowest
pHs.
The graphs form a V shape that visualize how
the rate digestion was more rapid towards the
middle pH of 6.8 and then slowed down
again.
4
5
6.8
0.47 (28
seconds)
8
1.83 (1 minute
50 seconds)
10
8
0
0
2
4
6
8
10
12
pH
•
Discussion Section
Hypothesis #1
• As the concentration of the enzyme Amylase
increases, the rate of starch disappearance
increases.
• A.K.A. The rate of starch disappearance is
directly proportional to the concentration of
Amylase acting on it.
Supported?
• Hypothesis WAS SUPPORTED, as seen in graph 1 the
time of starch disappearance increases relatively steadily
as the dilution/concentration of amylase decreased from
.50 to .075
• A.K.A The idea that amylase helps to digest starch is
supported. Also, when there is more (higher
concentration) of amylase, starch will be broken down
more quickly.
Supporting Background Info
• Supporting background info: “It [amylase] catalyzes the breakdown of starch.
•
•
When amylase reacts with starch, it cuts off the disaccharide maltose (two glucose
molecules linked together). As the reaction progresses, less starch will be present
and more sugar (maltose) will be present.” (2)
This helps explain why starch breakdown begins in the mouth; amylase is found in
human saliva, so as soon as a starchy food like a potato enters the oral cavity and
interacts with saliva, amylase begins to break it down into sugar.
Amylase is also secreted by the pancreas to continue starch digestion in the stomach.
(3)
(4)
Hypothesis #2
• Amylase will be most active at a small,
middle range of pH (6-8), and will not be
active at too high or too low a pH.
• A.K.A: Starch will disappear most quickly
at a middle pH range (6-8) and will take
much longer to disappear at too high or too
low a pH.
Supported?
• Hypothesis WAS SUPPORTED. As seen
in graph 2, starch disappeared most
quickly (only 30 seconds) at a middlerange pH of 6.8.
• The starch disappeared most slowly
(around 9 minutes or more) at the extreme
lows (2-strongly acidic) and extreme highs
(10.0-strongly basic) pH levels.
Background Info
• The effective range of pH was
hypothesized to be within 6 and 8 because
the body consists largely of water with a
pH of 7, and the different bodily fluids
largely range between 6 and 7.4. (5)
Sources of Error
•
•
•
Graduated cylinders, like most forms of measurement, have some degree of error, so
what looked like 5mL measured out may have varied slightly and may have caused
the time of disappearance to go from 10 to 20 to 50 instead of 10 to 20 to 40- which
would directly correspond to the decreasing concentration of amylase from .5 to .25 to
.125.
When the dilution was .075, the blue color continued to be slightly apparent even after
60 seconds but the lack of spaces in the tray did not allow for the experiment to
continue.
When measuring the amylase in cleaned-out graduated cylinders, some water
droplets may have been leftover and could have slightly diluted the amylase more
than it was supposed to be diluted, which could have lengthened the time of starch
disappearance, possibly accounting for the jump from 16.6 to 53.6 seconds instead of
the predicted proportional increase of approximately 16 to around 32 or 33 seconds.
What would happen at…
80 °C?
• Amylase becomes “denatured…a major
change from the native state to another
state without changing the primary
structure. ” (6)
• The speed of the atoms and the strength of
their collisions increase, which can
damage the molecular structuresometimes irreversibly. (6)
37°C.?
• This is the average body temperature and
therefore the most optimal environment for
amylase to react with starch.
22 °C.?
• This is about room temperature, which relatively cold in
•
terms of amylase. This colder temperature, however has
not been observed to greatly affect the reaction of
amylase with starch. (6,7)
Some theories suggest that amylase evolved to be able
to survive in colder temperatures. It is believed that those
enzymes which could not stand the cold died off, allowing
for the more temperature-resistant molecules to survive.
This did not occur with extremely hot temperatures
because such temperatures are rarely found in any
climate on earth.(6)
4°C.?
• Even at this somewhat extreme cold,
amylase continues to react effectively with
starch.(6)
• It is believed that amylase evolved to be
able to function at such low temperatures
due to naturally-occurring cold climates. (6)
Digestive Application:
Carboxypeptidase
Carboxypeptidase: Source, Location
of Enzyme Activity and Substrates
• The source of this digestive enzyme is the
pancreas 4
• The location of the enzyme’s activity: small
intestine 4
• Substrates for carboxypeptidase are
protein fragments 5
What is Produced From This
Hydrolysis Reaction?
• In order to break down a protein (polymer) into amino
•
•
acids (monomers), cells use a hydrolysis reaction  a
protein reacts with a water molecule to produce an
amino acid and a protein 7
Carboxypeptidase is secreted by the pancreas, and
speeds up the hydrolysis reaction between the protein
and the water molecule 8
The main products of this hydrolysis reaction are amino
acids which are then small enough to be absorbed by
the villi in the small intestine7
What Factors Effect Enzyme
Activity?
• As the pH level changes in the small intestine
•
•
and gradually becomes basic, more enzymes are
activated further that chemically break down
various nutrients into smaller molecules to allow
absorption 10
The ideal pH of the duodenum is 6 to 6.5 11
The ideal pH of the jejunum and illium is 7.8
pH Levels in the Digestive
System
Digestive enzymes
that are located in
the duodenum are
most active at a pH
of 6 8
Digestive enzymes
that are located in
the jejunum and
illium are most
active at a pH of
7.8 8
pH’s Effect on
Carboxypeptidase’s Activity
100%
7.8
Temperature’s Effect on
Carboxypeptidase’s Activity
• The temperature of the small intestine is
approximately 37 degrees Celcius7
• Small fluctuations in temperature change
will not effect carboxypeptidase’s activity9
• However, a big increase or decrease in
temperature will decrease the amount of
activity by carboxypeptidase11
Effect of Temperature on
Carboxypeptidase’s Activity
References
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11.
12.
http://www.chemistry.wustl.edu/~edudev/LabTutorials/Carboxypeptidase/images/cpep.jpg
“Laboratory #5: Enzymes,” http://www.und.nodak.edu, October 19 2010,
http://www.und.nodak.edu/dept/jcarmich/101lab/lab6/lab6.html
“Amylase,” wikipedia.ord, October 19 2010, http://en.wikipedia.org/wiki/Amylase
http://www.istockphoto.com/file_thumbview_approve/4643127/2/istockphoto_4643127-starchy-food.jpg
“What is the Normal pH of Blood, Urine and Saliva?”, www.enotes.com, October 19 2010,
http://www.enotes.com/science-fact-finder/human-body/what-normal-ph-blood-urine-saliva
“Amylase Enzyme: The Effects Of Temperature,” www.allsands.com, October 18
2010,http://www.allsands.com/science/amylaseenzymeh_wpp_gn.htm
“The Effect That Temperature Has on Enzyme Activity,” www.docshare.com, October 17
2010,http://www.docshare.com/doc/163073/The-effect-that-temperature-has-on-enzyme-act
Starr, Cecie and Ralph Taggart. Biology: The Unity and Diversity of Life. Pacific Grove, CA: Brooks/Cole, 2001.
Casiday, Rachel and Regina Frey. “Enzyme-Substrate Binding: Carboxypeptidase,”
http://www.chemistry.wustl.edu October 18 2010,
http://www.chemistry.wustl.edu/~edudev/LabTutorials/Carboxypeptidase/carboxypeptidase.html
Winsemius, David. “What are the pH Levels in the Stomach During a Titration of Saliva and Food?”
http://madsci.org October 18, 2010, "http://madsci.org/posts/archives/may98/892927858.Ch.r.html"
http://madsci.org/posts/archives/may98/892927858.Ch.r.html
Boudinot, Sally. “Anatomy of the Gastrointestinal Tract and Drug Absorption.” www.chemcases.com, October
19 2010, http://www.chemcases.com/pheno/pheno14.htm
“Temperature of a Healthy Human Body,” www.hypertextbook.com, October 19 2010,
http://hypertextbook.com/facts/LenaWong.shtml