Analysis of the Effects of Potato vs. Apple catalyzing Hydrogen peroxide

Shannon Moran

Anne Marie Hoskins

E.E Xu

Period 3

Effects of Different Peroxidases as a Catalyst: Apples Vs. Potatoes

Abstract:

We tested the differences between apples and potatoes as enzymes by using each as a peroxidase in a hydrogen peroxide reaction. If potatoes are used as a peroxidase in the hydrogen peroxide solution, they will generate more oxygen than if apples are used because potatoes contain more catalase and when catalase is added to hydrogen peroxide, there is an initial rapid evolution of oxygen.

Intro:

Enzymes are extremely efficient catalysts; they can break down, speed up, or control chemical reactions that would not occur under normal circumstances in the human body. Hydrogen peroxide is an important acid in our body that is produced in large quantities by cells (specifically white blood cells) to fight infection (ScienceDaily). However, too much hydrogen peroxide can alter the cell’s DNA and damage surrounding proteins. In order to keep the levels of hydrogen peroxide stable, the body produces an enzyme called catalase. Catalase is a fast working enzyme that can aid the neutralization of hydrogen peroxide into water and oxygen, as shown here: 2H2O2  ----> 2H2O + O2. One molecule of catalase can react to six million molecules of hydrogen peroxide in one minute (ScienceGeek).

Catalase is commonly found in peroxisomes, an organelle that acts similar to lysosomes, only it breaks down simpler molecules. During cellular processes such as photorespiration (glucose is broken down), hydrogen peroxide is generated:

                   glucose + oxygen --> gluconic acid + hydrogen peroxide + energy

Potatoes contain a lot of glucose because of their high starch concentration. Until a newly grown plant is able to convert sunlight into glucose, potatoes store huge amounts of starch for energy during the winter, since they exist as bulbs underground. Therefore, more glucose stimulates the production of hydrogen peroxide, which in turn forces the potato to contain more catalase. On the other hand, apples grow above the ground. They are supported by a multitude of leaves photosynthesizing for a longer time, making it unnecessary for an individual apple to store starch. Potatoes would act as a better catalyst than an apple in a hydrogen peroxide solution because they contain more catalase.( Monica Watchman)

Procedure:

1. Measure 20 ml of hydrogen peroxide in a small vial (35.5 mL).

2. Set up the program on the computer which documents the time(s) and pressure(atm) of the reaction.

3. Attach the sensor to the vial.

4. Add 1 cm^3 of first peroxidase to the H2O2

5. Start sensor and await results

6. Preform reaction for 120 Seconds

7. Repeat steps 3-6 with 2nd measured peroxidase

8. Denature both peroxidases using a general electric microwave (cook for one minute each)

9. Repeat steps 3-6 for each denatured peroxidase

Materials:

• General electric microwave
• Acculab Sartorius group scale
• 3 cubes of Honeycrisp Apple (1cm^3)
• 3 cubes of potato (1cm^3)
• Hydrogen Peroxide (Safeway Brand)
• Passport Chemistry Sensor

Figure 1	Figure 2	Figure 3
*	*	*

Figure 1: Measurement tools used. Figure 2: Apple peroxidase experiment setup. Figure 3: Pre-measured apple pieces.

Results:

mL of Oxygen Production Per Trial

	Apple	Potato
Trail 1	17.58mL	18.04 mL
Trial 2	18.25 mL	18.97 mL
Denatured	18.31 mL	17.11 mL
Average(trials 1&2)	Apple Avg: 17.915	Potato Avg:18.505

Summary:

We measured the pressure of a hydrogen peroxide reaction for 2 minutes each for two trials with an apple and two trials with a potato. We also used denatured apple and potato as a negative control.We used the computer program to measure the amount of pressure of the vial over time. Then we found the average pressure (atm) for each food piece and the volume of hydrogen peroxide lost during the reaction. Next, we divided the pressure and volume by the constant R=0.08206, the temperature (Kelvins) . By doing this, we would use the properties of the ideal gas law to determine the number of moles of oxygen produced (Pv=nRt). Finally, we multiplied the moles by the ideal gas constant 22.4 to find the volume.

Discussion:

Our hypothesis that If potatoes are used as a peroxidase in the hydrogen peroxide solution, they will generate more oxygen than if apples are used was proven in the data that we collected. In our apple trials, the average volume of oxygen produced was 17.92 mL. This is less than the amount of oxygen created by potatoes, 18.51mL. These results show that the peroxidase reacted more with potatoes because they contain more catalase than apples do. The data we collected showed that .59mL more oxygen was released when using a potato.

When comparing the graphs of the potato trails and the apple trials, the conclusion can be easily drawn that the potato was a significantly better catalase than the apple. The potato slopes up at a more constant rate while the apple does not increase in such a strategic manner.

Our experimental procedure had many flaws. One way we could have improved upon our experiment was to use new hydrogen peroxide, instead of an already opened bottle. Another mistake we made was that both the denatured apple and potato were considerably smaller than the other ones because we cooked them after measuring, therefore the surface areas were not constant. Also, our negative controls should have stayed at a constant rate, but they both had slopes. We also should have noted the brand and power of the microwave we used. The apple trails and the potato trials were done at different days therefore using slightly older hydrogen peroxide as well as variations in room temperature. We should have been more careful in controlling the environment in which the experiment was held.

References:

Wake Forest University Baptist Medical Center. "Hydrogen Peroxide Has A Complex Role In Cell Health." ScienceDaily, 4 Jan. 2008. Web. 20 Oct. 2013.

George, P. "Reaction Between Catalase and Hydrogen Peroxide." Nature.com. Nature Publishing Group, 12 July 1947. Web. 22 Oct. 2013.

Maass, Eric. "Re: Why Do Potatoes Contain Catalase?" Re: Why Do Potatoes Contain Catalase? Mad Sci Network, 28 Nov. 1998. Web. 20 Oct. 2013.

Wachman, Monica. "Why Do Potato Plants Store Starch in Their Roots? | EHow."EHow. Demand Media, 29 Nov. 2009. Web. 21 Oct. 2013.