The Effect of Concentration, pH,
and Temperature of Salivary
Amylase on the Rate of Starch
Disappearance
By: Caroyln Gee, Helen Zhang,
Amanda Kim, Katie Senter
Results
The Effect of % Amylase Concentration
on the Time of Starch Disappearance
~Graph 1 depicts the data
collected from the first
experiment, which tested the
Effect of % of Amylase
Concentration on the Time
of Starch Disappearance.
~As depicted, the average
time in seconds of starch
disappearance lessens as the
% concentration of amylase
increases.
The Effect of pH on the Time of Starch
Disappearance
~Graph 2 depicts the data
collected from the second
experiment, which tested the
effect of pH on Starch
Disappearance. As depicted in
the graph, when the pH was low
(more acidic), the time required
for the disappearance of starch
increased.
~Likewise, when the pH was
high (more basic), the time
required for the disappearance
of starch increased as well.
+Note: After 9 minutes, the experiment was stopped
because it was such a long time and the amylase may
have lost its shape and stopped functioning properly
Discussion
Effect of % Amylase Concentration on Time of
Starch Disappearance Hypotheses - Rejected or
Supported?
1.) Increased amylase concentration
will decrease time of starch
disappearance.
SUPPORTED
~Evident by the trend line in graph 1,
time before starch disappearance
decreases as amylase concentration
increases. When the concentration is
.25% amylase, the average time for
starch disappearance was 16.6
seconds, whereas when the amylase
concentration was only about .03%,
223.6 seconds were required for
complete starch disappearance
Do the results make sense?
• It makes sense that as the enzyme
concentration increases, the time of
starch disappearance will decrease
because there are more chances for
substrates to react with a higher
concentration
• Since the rate of reaction is increased,
the time it takes for the starch to
disappear decreases
• Other research also supports the data
collected--this graph shows the same
trend--as enzyme concentration
increases, the time to starch
disappearance decreases
http://www.und.nodak.edu/dept/jcarmich/101l
ab/tests/test1.html
Relevance in Reality
• Concentration of amylase in saliva is 94 x 10^3 U/L (4)
• It makes sense that the concentration would be very low
because digestion of starch only starts in the mouth with
salivary amylase, and finishes later in the digestive system
The Effect of pH on the Time of Starch
Disappearance Hypotheses - Rejected or
Supported?
2.) As pH nears the optimum
temperature for amylase function, time
of starch disappearance will decrease.
SUPPORTED
~In graph 2, with a pH of 6.8, the
amylase took only approximately 30
seconds to break down all the
starch. However, the trend line for the
graph is shaped like a parabola with 30
seconds as the minimum value - with a
pH of 10, the starch took an average of 8
minutes to disappear, and with a pH of
2, at least 9 minutes was required for the
starch to disappear
+Note: After 9 minutes, the experiment was stopped
because it was such a long time and the amylase may
have lost its shape and stopped functioning properly
Do the Results Make Sense?
• It makes sense that the time of starch
disappearance be the least at pH 6.8
because as shown by other researchers, the
optimum activity of amylase is at a pH
level around 6
• Since the activity level is at an optimum, it
will take less time for the starch to react
with the amylase and disappear
• Likewise, at pH 8 there is less amylase
activity, but the time of starch
disappearance increased
• If the pH is too high or low, the enzyme
would become denatured, causing the
decrease in activity and increase in time of
starch disappearance
(7) <http://genesdev.cshlp.org/>.
Relevance in Reality
• The pH of the human esophagus ranges from about 5-6, and
according to the graph on the previous slide and from
collected data, salivary amylase functions best between pH
levels of 5 and 7, with maximum effect at a pH level of about
6 (6)
• Thus, the lab data collected is logical because amylase
cleaved starch into simple sugars at a faster rate the closer
the pH of the amylase-starch mixture was to 6.8
Sources of Error
and how future experiments can be
improved
Sources of Error
• In Experiment #1, in one of original pieces of data, it took 90 seconds for
starch to disappear when mixed with a .125% amylase solution. When the
starch was mixed with a .0625% amylase solution, however, it took 50
seconds for starch disappearance. This outlier may be due to the amylasestarch mixture not being mixed properly with the iodine for the test that
resulted in the 90 second starch disappearance.
• Furthermore, in Experiment #1, one lab group reported that the .0625%
amylase solution took 180 seconds to break down all of the starch, whereas
the other groups recorded 50-70 seconds for complete starch elimination
• These strange outliers can possibly be eradicated in future experiments if one
participant supervised the iodine and amylase-starch mixture to make sure it
was properly mixed in between each 10 second interval.
Sources of Error continued...
• There was a time lapse between when the amylase and
starch was mixed and when the mixture was added to the
iodine (error with experiment that cannot be completely
prevented).
• However, the time lapse can be improved in future
experiments by setting a certain amount of time before the
amylase and starch mixture is added to the iodine or by
starting the timer the moment amylase is mixed with starch.
How can this experiment be improved?
~ The iodine should be mixed immediately with the starchamylase mixture so that the time it takes for the starch to
disappear is most accurate.
~ There should be a given shade of the iodine when the time
should be stopped. This would improve consistency and
accuracy of time of starch disappearance because it would
clarify what to look for.
Graph of Amylase Function Regarding
Temperature
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Starch Disappearance at 80, 37, 22, and
4 degrees Celsius
o
o
According to other
experiments, the time of
starch disappearance is
least at a temperature of
37 degrees Celsius
This makes sense since
the "normal"
temperature of human
body when taken in
mouth is 37 degrees
Celsius
(8) http://www.associatedcontent.com/article/8
679/the_effect_of_tem
perature_on_amylase_pg2.html?cat=5
Digestive Application
Trypsin and Chymotrypsin
Source: found in pancreas
~Active in small intestine,
especially in small animals
where pH is around 8 (2)
which is close to the pH level
of the small intestine, and
works best at normal body
temperature (95-99.5 degrees
Fahrenheit) (3)
~The substrate for this
enzyme is protein (2)
~Major products include
protein fragments and
peptides (2)
Trypsin and chymotrypsin
are structurally very similar,
although they recognize
different substrates (1) :
~Trypsin acts on lysine and
arginine residues (1)
~Chymotrypsin acts on large
hydrophobic residues such as
tryptophan, tyrosine and
phenylalanine (1)
Bibliography
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3) "Normal Body Temperature: Rethinking the Normal Human Body Temperature." Harvard Health
Publications. Web. 18 Oct. 2010.
<http://www.health.harvard.edu/press_releases/normal_body_temperature>.
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<http://www.und.nodak.edu/dept/jcarmich/101lab/lab6/lab6.html>.
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http://www.rivm.nl/interspeciesinfo/intra/human/mouth/
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<http://genesdev.cshlp.org/>.
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http://www.associatedcontent.com/article/8679/the_effect_of_tem
• perature_on_amylase_pg2.html?cat=5
Bibliography Continued
(9) “Effect of Incubation on Temperature on Amylase” Fri Oct 15 2012
http://www.google.com/imgres?imgurl=http://www.pharmainfo.net/files/images/stories/CTBT/EffectOfIncubationTe
mperatureonamylasea
ctivity.jpg&imgrefurl=http://www.pharmainfo.net/articles/production-%25CE%25B1-amylase-agricultural-byproductshumicola-lanuginosa-solid-statefermentation&usg=__fXPlL43cX4jVnCfIy9kF1DHbWwA=&h=281&w=450&sz=15&hl=en&start
=0&zoom=1&tbnid=60w53oI8fZYsOM:&tbnh=125&tbnw=200&prev=/images%3Fq%3Damylase%2Btemperature%2Boptim
um%26um%3D1%26hl%3Den%26safe%3Dactive%26sa%3DN
%26biw%3D986%26bih%3D816%26tbs%3Disch:1&um=1&itbs=1&iact=rc&dur=375&ei=PjC3TN3oNYT6lwfRqIS7DA&oei=P
jC3TN3oN
•
YT6lwfRqIS7DA&esq=1&page=1&ndsp=16&ved=1t:429,r:3,s:0&tx=108&ty=86&safe=active
Thank You!
Questions?