The Effect of Temperature on the Activity of the Enzyme Catalase
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The catalase is added to hydrogen peroxide (H²0²), a vigorous reaction
occurs and oxygen gas is evolved. This experiment investigates the
effect of temperature on the rate at which the enzyme works by
measuring the amount of oxygen evolved over a period of time.
The experiment was carried out varying the temperature and recording
the results. It was then repeated but we removed the catalase (potato)
and added Lead Nitrate in its place, we again tested this experiment
at two different temperatures and recorded the results.
Once all the experiments were calculated, comparisons against two
other groups were recorded. With this information we were able to
identify any patterns and similarities.
The higher the temperature of water, potato and H²O², the rate at
which the Enzyme will work will be faster therefore producing more
The reaction will be the same without the catalase (potato). Therefore
in both experiments the Enzyme will work more rapidly and produce more
To test the hypothesis.
Hydrogen Peroxide Solution (20%)
The skin of the potato was removed using a scalpel and then cut into
1cm², using a ruler to measure the size of each cube, four cubes are
required for each experiment, and therefore at least 36 cubes are
required for the full experiment to take place. Fill a beaker half way
with water, and place a thermometer in the water. Allow the
thermometer to warm to room temperature to gather an accurate reading,
and measure the temperature, using the thermometer. A measuring
cylinder was used to put 10ml of Hydrogen Peroxide Solution into a
test tube, and then four potato cubes were placed into the test tube.
The mouth of the test tube was plugged with a delivery tube; the other
end of the delivery tube was placed in another test tube that was
filled with water. The stop-clock was set for one minute. The test
tube that's filled with water was observed, the number of oxygen
bubbles that are released in one minute were counted. Calculations
were noted before moving onto the next experiment. Each new experiment
that is taken place, ensure a new test tubes, new potato, fresh new
H²O² solution and fresh new water is used. A Bunsen Burner was lit
with matches; the beaker of water was placed on top of the gauze,
which was on top of the tri-pod, above the Bunsen burner, heat the
water, the thermometer was placed in the beaker. The temperature was
noted for each experiment. The experiment continued with the water at
different temperatures e.g. 25°, 35°, 45°, 50° and 60°. The results
were recorded indicating the number of oxygen bubbles released at each
The experiment was repeated at two different temperatures e.g. 20° and
32°, following the above guidelines, a pipette was used to add five
drops of Lead Nitrate to the mixture. Both results were recorded.
The experiment was repeated again, at two different temperatures e.g.
20° and 32°, following the above guidelines, removing the potato
(enzyme - catalase), and adding five drops of Lead Nitrate. Both
results were recorded.
The following table indicates the results and calculations of our
experiments. (Table 1).
Temperature of Water °C
Number of Oxygen Bubbles Released in 60 seconds: (Potato & H²O²)
This experiment was noted from three different groups and a comparison
was made. As noted in the table below. (Table 2).
Temperature of Water °C
Number of Oxygen Bubbles Released in 60 seconds: (Potato(4 x 1cm²) &
H²O²(10ml)) - Our Results:
Potato (5.37grams)& H²O² (10ml)
Potato (1 x 1cm²)& H²O²(5cm³)
By looking at the graph (see Diagram 1, attached), you will see that
different temperatures were used, as well as different volumes of
potato (enzyme - catalase) and H²O². This gave a completely varied
result, but indicated that the higher the temperature, the higher the
amount of oxygen bubbles were released. It also indicated that the
more potato (enzyme - catalase) that was used, the faster the
Temperature of Water °C
Number of Oxygen Bubbles Released in 60 seconds: (Potato, H²O² & Lead
Number of Oxygen Bubbles Released in 60 seconds: (H²O² & Lead Nitrate)
The above table (Table3) demonstrates the different reactions that
occurred when the experiment was repeated with Lead Nitrate, and then
again with Lead Nitrate but without the potato. Each column represents
the findings of the three groups; the first group is our own results.
This would conclude that my hypothesis for the first experiment
(potato, hydrogen peroxide) was supported by the experiment. This was
indicated by the number of oxygen bubbles that were released. Showing
that at the temperature of 50° eighty-four bubbles were released,
proving that the higher the temperature the faster the reaction of the
However, my conclusion on the experiment where the potato was removed
and lead nitrate added, it clearly showed that there was no reaction
at all. This was demonstrated by my results as well as the two
comparisons I made.
Analysis and Discussion:
Enzymes are globular proteins, which are polymers of amino acids. They
range in size from 1 x 104 daltons to 1 x 106 daltons with the
majority being in the 105 range. Some enzymes have extra molecules
other than amino acids, which assist in the reaction they carry out.
The protein portion of an enzyme is called the apoenzyme. The
non-protein part of an enzyme is called a cofactor. Cofactors can be
loosely bound; coenzymes are tightly bound, into prosthetic groups.
The complete enzyme (apoprotein + cofactor) is called the holoenzyme.
Enzymes are proteins that catalyze (speed up) chemical reactions.
Enzymes increase reaction rates by a factor of about 1 million (ref:
Marieb, Elaine N). They do this by lowering the activation energy
needed to get a reaction to go forward. All enzymes are specific to
single chemical reactions or a small group of related reactions. Each
specific enzyme determines which reaction will occur and be speeded
up, this means that unwanted chemicals or reactions are reduced.
The results of my experiment indicate that at the temperature of 35°
the reaction was the slowest with only twenty-seven oxygen bubbles
being released; whereas at the temperature of 50° the reaction was the
highest at eighty-four oxygen bubbles being released. This indicated
that the higher the temperature the faster the reaction. This
experiment was carried out various times by different groups, and it
indicated that the amount of catalase (potato) was a significant
factor on how slow or quick the reaction, the more potato the quicker
The results could vary very much, depending on the amount of potato
and H²O² that was used; this is proving in my comparisons'. Showing
that the group that used the least amount of potato (1 x 1cm²) and the
least amount of H²O² (5cm³) got the lowest reaction. Improvement could
be made by ensuring that every experiment that is carried out uses the
exact amount of H²O² and the same amount of potato. This would clearly
give a more accurate reading.
I would suggest that in future experiments 4 x 1cm² of potato, 10ml of
H²O², and temperatures at 20°, 30°, 40°, 50° and 60° are tested.
Therefore all results would be more accurate and a better comparison
could be made.
Catalase is one of the most potent catalysts known. The reactions it
catalyses are crucial to life. Catalase catalyses conversion of
Hydrogen Peroxide; a powerful and potentially harmful oxidizing agent
to water and molecular oxygen. Catalase also uses Hydrogen Peroxide to
oxidise toxins including Phenols, Formic Acid, Formaldehyde and
Catalase like all enzymes has an optimum temperature and pH at which
it works best. This may differ according to the source of the catalase
- catalase from liver could have a higher optimum temperature than
catalase from potato. Experiments can be done to find out the optimum
for your catalase. The pH optimum of potato catalase is pH 7.6.
The pH is the measure of the acidity or alkalinity of a solution. An
acidic solution has many hydrogen ions (H+) and a pH below 7. An
alkaline, or basic, solution has very few hydrogen ions and a pH above
7. A neutral solution has a pH of 7.
An enzyme that is found in the cells of many living tissues is
catalase it speeds up a reaction which breaks down hydrogen peroxide,
a toxic chemical, into 2 harmless substances - water and oxygen. The
reaction is as follows:
2H2O2 ----> 2H2O + O2
This reaction is important to cells because hydrogen peroxide (H2O2)
is produced as a result of many normal cellular reactions. If the
cells don't break down the hydrogen peroxide, then they would be
poisonous and die.
There are three essential steps in the participation of the mechanism
of enzyme action:
1. The enzyme must attach itself to the substance(s) on which it
works. These substances are called the substrates of the enzyme.
Substrates attach to a particular part of the enzyme's surface; this
is called the active site. This is very much like a jigsaw puzzle, and
particular substrates attach and fit into the enzymes. This is called
2. Internal rearrangement of the enzyme substrate forms the product.
3. The enzyme releases the product, showing the catalytic role of the
The process then continues again and again with the "free" enzyme to
locate its matching substrate(s). Enzymes can be found in every organ
of the body. For example, they can change starches, proteins, and
sugars into substances the body can digest. Blood clotting is an
example of enzymes at work. Enzymes exist in the mouth (saliva),
stomach (gastric juice), and intestines (pancreatic juice, intestinal
juice, and intestinal mucosa).
I believe the results I obtained showed precisely the higher the
temperature the quicker the reaction, but when the catalase is removed
no reaction occurs.
Date of Publication:
Marieb, Elaine N
Human Anatomy & Physiology, 3rd Edition
Holyoke Community College
Wancke, J. H Christopher
Chemicals of Life
Guyton, M. D Arthur
Basic Human Physiology: Normal Function & Mechanisms of Disease
www.biologylab.co. Stephen Fuller
Observing an enzyme
Kansas City, Missouri School