Livingston, Tso, Fuhriman

Analysis of Various Sources of Peroxidase in Hydrogen Peroxide

E. Fuhriman, W. Livingston, J. Tso

Miramonte High School Orinda, CA 94563

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Introduction & Hypothesis

Peroxisomes contain oxidizing agents that can break hydrogen peroxide (H2O2) down into water (H2O) and oxygen gas (O2(g)). They have many functions including filtration of toxins in the body and assisting photosynthesis in plants. Hydrogen Peroxide (H2O2) is broken down into water and oxygen (2H2O2 (aq)→ 2H2O + O2(g))  when a peroxidase is present. The peroxidase acts as a catalyst which lowers the activation energy, or the amount of energy needed for a reaction to occur. Simultaneously, the catalyse releases energy by decomposing hydrogen peroxide by breaking its bonds.

We tested if putting more than one source of peroxidase will cause hydrogen peroxide to break down faster. To compare which source of peroxidase and whether multiple sources of peroxidases will cause the faster rate of reaction, we ran two trials; one with just yeast and the other with oats and yeast. Because of the added peroxidases, the hydrogen peroxide will become decomposed faster, thus the trial with oats and yeast should have the fastest rate of oxygen production and decay of hydrogen peroxide.

Materials:

Material	Specifics	Quantity (per trial)
Hydrogen Peroxide	3% Concentration	10 mL
Active Yeast	1 gram suspended in 10 mL of 40°C water	1 mL
Old Fashioned Oats	Quaker brand	1 gram
USB Link Pressure Sensor	DataStudio	1
Graduated Cylinder	10 mL, plastic	1
Laptop	MacBook Pro	1
Temperature probe sensor	DataStudio	1
Glass chamber with top	combined volume of tube and chamber is 42 mL	1
Tube extension	Attached to glass chamber, combined volume of tube and chamber is 42 mL	1
pipette	plastic	1
small bowl for yeast and water solution	glass	1

Procedure:

1. Take all of the proper measurements, which consisted of the air pressure in atm, the volume of the container and tubes we used (we filled the containers with water and measured the volume of that water), and found the room temperature in Kelvins.

2. Attach the pressure sensor to the computer and made sure we could attach the experiment container to it quickly.

3. Heat up 10 mL of water to 40°C and add 1 gram of yeast.

3. Put 10 ml of Hydrogen Peroxide into our container, and then add the yeast solution.

4.After quickly connecting the container to the tube attached to the pressure sensor (see Figure A below), we tracked the pressure rise until we got a steady rate of increase.

5. After finding the rate, we repeated the experiment to make sure our data is accurate.

6. Collect and organize the data for later use.

6.After finishing the trials for yeast by itself, we cleaned and dried the containers for the next test.

7. We repeated steps 3 through 6, except instead of only adding 1 mL of yeast solution, we also put in 1 gram of oats and ran the same test.

Figure A: the setup

On the bottom of the picture, there is a chamber that holds the solution. A tube connects the chamber to the pressure sensor, which measures the pressure and displays the data on the computer.

Figure B: the yeast, oats, and hydrogen peroxide that was used

Unfortunately, the fact that we didn’t actually measure the temperature of the water may have caused an error in our experiment. The water started at 40 degrees Celsius and may have regressed to room temperature by the time we conducted the experiment. This may have affected how the experiment reacted which in turn might not give us a correct molar value when putting the temperature in the equation. Also, the warmer water can accelerate the rate of decomposition. The decomposition reaction is slower at room temperature. This could be improved by keeping the yeast in a bath of 40°C water so that the temperature stayed constant. Another potential error is with the yeast. The yeast was just in a solution, so it settled to the bottom. We tried to stir it around before taking any for our test, but not all of it was completely mixed the whole time. This could have been avoided if we kept swirling the container to keep the mixture evenly mixed.

Equations

We used the equation pv=nrt.

(pressure change after 20 seconds)*(volume)=(moles of O2)(.0821)(temperature in kelvins)

This equation gives us the number of moles of oxygen created.

Results

Figure C:

This experiment clearly shows that the oats helped to break the hydrogen peroxide down. Our first trials (with only yeast) resulted in lower oxygen production rates, while the trials with both yeast and oats resulted in more oxygen production. This is also shown by the slopes of these lines; the average slope for the trials with only yeast is .0064, while the slopes of the lines showing yeast and oats is .0087.

Figure D:

This graph shows that there was a significant increase of moles of O2 created when the oats were added to the solution. The average number of moles of O2 created with just yeast is 27.45, while the trials with yeast and oats averaged 25.3 moles.

Discussion and Conclusions

The goal of this experiment was to prove that adding oats and yeast would break oxygen down faster than just yeast. Our prediction was that having more peroxidases will speed up the rate of the reaction, so the trial with the oats with yeast will have the fastest rate.

To make sure not to invalidate the data, we controlled the mass of the materials used. We made sure to use the same amounts of yeast and oats (1 gram each). From our experiment, we encountered that oats do help the reaction decompose faster, the trials with the oats with the yeast (shown in the graph above) has a higher oxygen production rate and reaches 1.15 atm while the trials with just yeast only reach up to 1.1-1.11 atm, both at 20 seconds. Therefore, rate of the reaction is faster when there are more than one source of peroxidase present, does break down hydrogen peroxide faster than just one source of peroxidase.

References

Clark, Jim. "Ideal Gases and the Ideal Gas Law." Ideal Gases and the Ideal Gas Law: PV = NRT.

N.p., 2010. Web. 22 Oct. 2013.

<http://www.chemguide.co.uk/physical/kt/idealgases.html>.

Goodwin, Doug. "Structure and Function of Heme Enzymes." Goodwin Laboratory. N.p., n.d.

Web. 22 Oct. 2013. <http://www.auburn.edu/~goodwdc/>.

Schluter, A., Real-Chicharro, A., Gabaldon, T., Sanchez-Jimenez, F. and Pujol, A. (2010)

PeroxisomeDB 2.0: an integrative view of the global peroxisomal metabolome. Nucleic

Acids Res, 38, D800-5.