Effects of pH on the Function of Enzymes
Glen Rock High School
Effects of pH on the Function of Catalase
Problem: How does the pH of a cell affect the function of the enzyme catalase? Introduction
In this lab, we experimented the effects of pH on the function of the enzyme catalase. Catalase is an enzyme that brings about the reaction by which hydrogen peroxide is decomposed to water and oxygen (Encyclopedia Britannica). The chemical reaction is shown as 2H2O2 = 2H2O + O2 (Keilin and Hartree 397). The reaction involves primarily the adsorption of hydrogen peroxide at the catalase surface. The decomposition of hydrogen peroxide by catalase is regarded as involving two reactions, namely, the catalytic decomposition of hydrogen peroxide, which is a maximum at the optimum pH 6.8 to 7.0, and the "induced inactivation" of catalase by the oxygen produced by the hydrogen peroxide and still adhering to the catalase surface (Williams). This is a reaction commonly seen in the liver, as the catalase breaks down these harmful chemicals through this process.
Catalase, again is a common enzyme found in nearly all living organisms mostly in the liver, where it functions to catalyze the decomposition of hydrogen peroxide to water and oxygen (www.princeton.edu). In this lab this catalase was used to decompose the hydrogen peroxide. Hydrogen peroxide is a colorless fluid with the formula H2O2 and it is the simplest peroxide. A solution containing more than 8% of this is corrosive to the skin (Encyclopedia Britannica). Sodium hydroxide, or NaOH is a manufactured chemical that is a base and present in several domestic cleaning products (www.atsdr.cdc.gov). In this lab we use 0.1M and 0.5M of this solution which is 13pH and 13.7pH (Helmenstine). On the other hand, hydrochloric acid is an acid used in the production of chlorides, fertilizers, and dyes, in electroplating, and in the photographic, textile, and rubber industries. Hydrochloric acid is corrosive to the eyes, skin, and mucous membranes (www.epa.gov). In this lab we use 0.1M and 0.5M of this solution which is 0.3pH and 0.1pH (Helmenstine). Finally, water, H2O is a substance all organisms need to survive and it has the pH of 7 (www.ndu.edu).
For this experiment, I will test the effects of pH levels of cells on the function of catalase by measuring the amount of oxygen bubbles formed after hydrogen peroxide is added to a 1cm³ piece of potato that is soaked in different types of solutions. I predict that if the potato has a neutral pH (close to 7), then the function of catalase will be at its maximum capacity because our bodies have a neutral pH and our livers, which contain catalase, work perfectly fine even in these conditions. This study is worth pursuing because catalase helps in the process of breaking down harmful chemicals such as hydrogen peroxide into unharmful substances such as water and oxygen and if we are able to find out the environment in which catalase works best, we can further our knowledge on catalase and possibly detoxify substances that are severely toxic, in the future. Scientists can possibly detoxify substances such as lead which is a major toxin to us, with the help of enzymes, after we uncover more information on catalase.
5 labeled test tubes
Test tube rack
Mortar and pestle
0.5M Hydrochloric Acid (HCl)
0.1M Hydrochloric Acid (HCl)
0.5M Sodium Hydroxide (NaCl)
0.1M Sodium Hydroxide (NaCl)
1.) Label the 5 test tubes 1-5
2.) Cut the potato with a knife on the cutting board into five 1 cm³ pieces. 3.) Take one of the potato cubes and crush it into a mushy state with the mortar and pestle. 4.) Using a scoopula, take all of the mushed potato and put it in test tube 1 5.) Set the stop watch for 45...
Cited: Catalase. (n.d.). Retrieved October 30, 2014, from
Catalytic Decomposition of Hydrogen Peroxide by Potassium Iodide. (n.d.). Retrieved October
30, 2014, from http://cldfacility.rutgers.edu/content/catalytic-decomposition-hydrogen-peroxide-potassium-iodide
Helmenstine, A. (n.d.). What You Need to Know to Calculate pH. Retrieved October 30, 2014.
Hydrochloric Acid (Hydrogen Chloride). (2013, October 18). Retrieved October 30, 2014, from
Keilin, D., & Hartree, E. (1938). On the Mechanism of the Decmposition of Hydrogen Peroxide
The Editors of Encyclopædia Britannica. (n.d.). Catalase (biochemistry). Retrieved October 30,
Toxic Substances Portal - Sodium Hydroxide. (2002, April 1). Retrieved October 30, 2014.
Water is everywhere... (n.d.). Retrieved October 30, 2014, from
Williams, J. (1928, March 20). The Decomposition of Hydrogen Peroxide by Liver Catalase.
The Rockefeller University Press
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