The Effect of Temperature on Amylase
We have been asked to investigate what affect temperature has on
I believe that the heat will affect the enzyme as the temperature is
changed. I fell that the breakdown of starch will be quicker as the
heat is increased. I think that the optimal temperature level will be
30-40 degrees, which is around body temperature.
What is an enzyme?
An enzyme is a biological catalyst that speeds up a chemical reaction
without being destroyed itself. The enzymes amylase
converts a complex
sugar such as starch, into a simple sugar such as glucose:
The enzyme amylase
is found in the mouth and the small intestine.
How is an enzyme affected by heat?
All enzymes will have an optimal temperature. This temperature will
depend on the enzyme itself. Amylase will have an optimal temperature
of about 35-400c.
The graph above shows what happens to the rate of reaction
temperature is increased. The graph has three main areas:
A. Here the rate of reaction is very low. When the temperature is
low (about 00c) the molecules do not have very much energy.
Molecules need to interact with enough energy in order to react.
When the temperature is low there is not enough energy for the
molecules to react. As a result the rate of reaction is reduced.
B. At this point the enzyme is working at an optimal level. The
molecules have enough energy to react and due to their motion
(movement) they are colliding at a greater rate. This will result
in a lot more interactions and a higher rate of reaction.
C. At this point the rate is reduced. The reason for this is that
the enzyme itself has become destroyed or denatured. The molecules
have enough energy to react but because the enzyme has become
denatured they are unable to react with the starch molecules. As a
result of this limited interaction the rate is greatly reduced.
The diagram below explains this:
The diagram above shows the effect of amylase as the temperature
differentiates. The grey box represents the starch and the 'C' shaped
object represents the amylase. The starch bonds with the amylase at an
area called the Active site. Once it has bonded with the enzyme the
starch is broken up into glucose. The active site only allows starch
to bond nothing else will fit! (Diagram A). When the temperature is
increased to around 45-550c the enzyme becomes denatured. As a result
the active site changes shape and no longer allows the starch to bond
with it, as the starch molecule can't fit into the amylase (Diagram
B). This results in a lower rate of reaction.
* 2% amylase
* 2% starch
* Water baths (20, 30, 40, 500c)
* Syringes (to measure quantity of starch/amylase)
* Pitted tiles
1. Collect The Apparatus
2. Place 5ml Of Starch And 5 Ml Of Amylase Into Two Test-Tubes.
Place the Test Tubes Into A Water Bath.
3. Leave The Test Tubes There For 2 Minutes, And then Mix Them
Together. (Start The Timer)
4. Place A Few Drops Of Iodine Into Each Pit Of The Tile.
5. After 30 Seconds Take A Sample Of The Starch And Amylase And
Place it In The First Pit. Each Pit Will Represent 30 Seconds.
6. Keep Taking Samples Every 30 Seconds Until The Sample Goes Brown.
7. Make A Note Of The Time.
8. Repeat Using A Different Temperature.
To make sure I kept this experiment hazard free I used important
safety procedures. The main one was to wear safety goggles to protect
my eyes from the chemicals as they can damage your eyes. In addition
to this I also made sure that my skin did not come into contact with
the amylase, as this is an irritant. I made sure not to get any water
onto the electrical equipment as we were using water baths that were
run on electricity. The final but still important point is to locate
the eye treatment in case of an emergency.
To obtain the best results I had to make sure that I did a fair test.
I did this simply by making sure that I used the same amount of starch
as I did amylase throughout the experiment, also I didn't mix the
starch and amylase until they acclimatised to the temperature of the
water. I did this by leaving the starch and amylase in different test
tubes in the same temperature for the same amount of time, and then
mixed them into the same test-tube. I also made sure that the water
bath stayed at the same constant temperature.
In total I done this experiment six times all at different
temperatures, these were at 0,10,20,30,40,50 and 60 degrees. The first
sets of tests were done at a temperature of 0 degrees, this took 12.6
minutes, but as the temperature rose the time it took to react
quickened. At 30 degrees the time to react only took 5 minutes this
time kept rising until it reached its optimum temperature/point. This
temperature was at 40 degrees Celsius. Once it reached this point the
time that the enzyme took to react steadily declined from 3.2 minutes
at 40 degrees, until 9.6 minutes at 60 degrees. I also predict that
the time would of kept falling until no reaction took place, but we
had to stop our experiment at 60 degrees. There are some trends in the
data as it is a curved graph; all results went as planed apart from
one anomaly. This anomaly occurred at 20 degrees, but other than this
the experiment went without a problem, the way I expected. What i
predicted to happen in my hypothesis was correct, the time the
reaction took to react decreased, when the heat rose then when it got
to 40 degrees (Body temperature) it started to take longer periods of
time to react.
My results are simple the hotter the temperature the quicker the rate
My original hypothesis was correct, 'I believe that the heat will
affect the enzyme as the temperature is changed. I fell that the
breakdown of starch will be quicker as the heat is increased. I think
that the optimal temperature level will be 30-40 degrees, which is
around body temperature.' I knew that this would be a rough guide to
what would happen, as this reaction takes place inside the human body
and the human body is around 40 degrees hot, it made sense that this
reaction would work better in the environment that it has to work in.
My experiment didn't go without and problems, I recorded an anomaly in
my set of results At 20 degrees. I fell that this anomaly occurred
because to see if the reaction had finished we had to see if the
mixture turned brown when mixed with iodine, but there are many shades
of brown. This didn't help the fact that we had to use just are eye to
try and judge when the mixture did turn brown, which is not very
accurate. There are many was that we could have improved this
experiment and made it more accurate, the main thing we could have
done is used a light sensor instead of human eyes. The spectrometer
would have been 100% accurate in defining the shade of brown and
ultimately told us when the amylase and starch had truly mixed, this
is the only way that this experiment could have been done with such a
degree of accuracy. I could take this experiment to a greater depth by
different means. I could test the effect of amylase in a cold-blooded
reptile and see if the rate of reaction differs from that of the rate
of reaction in us humans. But this will only reinforce my knowledge of
the optimum temperature the amylase will react at.