Factors Affecting the Rate of Catalase Activity

Topics: PH, Catalase, Enzyme Pages: 10 (3090 words) Published: February 9, 2013
Factors affecting the rate of catalase activity

The extent at which environmental factors affect the rate of catalase activity was discovered in this lab. The assay system, in which a filter paper disc was dipped into the enzyme and submerged using a stirring rod in a test tube filled with 20mL of hydrogen peroxide, was used to test several enzyme factors. As the saturation of hydrogen peroxide increased the rate of reaction increased as well. When the enzyme concentration increased the rate of catalase activity increased too. When catalase was subjected to an increase of temperature changes, the rate of reaction increased. Once the protein denatured around 100ºC the catalase activity decreased. Catalase operated with a high efficiency when the pH of the enzyme was 7. As the catalase pH was altered to acidic or basic, the rate of reaction decreased.


Catalase is an enzyme that promotes the decomposition of hydrogen peroxide to water and oxygen gas: H2O2  H2O + O2. Hydrogen peroxide is a potential hazard for the body, which is why it is used to kill bacteria (WKU, 2010). Cells would die if hydrogen peroxide is not broken down by catalase. The activation energy for the decomposition of hydrogen peroxide is reduced from 72 to 20kcal/mol with the presence of catalase. Catalase is specifically found in the peroxisome, a membrane bound organelle (Xiaoling Li, 2002). Changing the concentration of the substrate and enzyme CiVf = CfVi(1) alters the environmental factors and affects catalase activity. When a hot plate and ice water were used to create water baths to change the temperature, the rate of reaction would be altered accordingly. 0.1 mol of NaOH and HCL were used to create an acidic or basic solution of catalase. Changing the pH of catalase would affect the expected enzyme activity.


The purpose of this lab is to determine how environmental factors: pH, temperature, enzyme concentration, substrate concentration, and catalase activity in different tissues affect the rate of reaction


How does changing the substrate concentration affect the activity of catalase? How does changing the enzyme concentration affect the activity of catalase? When the temperature is altered, how is the activity of catalase affected? If the pH of catalase is changed, how is the activity of catalase altered? How does catalase activity vary between tissues?


When the substrate concentration is decreased, the enzyme activity will decrease accordingly. The rate of enzyme activity will amplify when the concentration of enzymes is increased. When the temperature is increased slightly, the rate of reaction will increase until the optimum value is reached and catalase is denatured. Catalase operates under a certain pH, the enzyme will denature when the pH is changed significantly. Apparatus

- electronic balance
- 2 400mL beakers- 250mL erlymer flask - 100mL graduated cylinder - ring clamp - general clamp
- thermometer
- food processor
-stirring rod
- 4-6 25mL beakers
- forceps- plastic shot glass
-Petri dish - stop watch
- goggles
- hot plate
- cord stopper
- test tube holder
-insulated tongs
- 1L flask
- reaction chamber- 6-8 test tubes
- rubber tube- test tube rack- retort stand
- pen
-plastic ice container


- distilled water
- paper towel- pH paper
- paper disc
-tape - buffer 7
- HCl
- hydrogen peroxide 3%- red delicious apple
- 0.1 mol NaOH

- cheesecloth
- calf liver
-veal muscle
- golden potatoes- parafilm
- 0.1 mol HCL


Part A: substrate concentration (assay technique)

1.add 20ml of 3% H2O2 to a test tube and measure depth
2.use tweezers to coat filter paper disc in the catalase enzyme 3.place the paper disc onto the stirring rod and submerge to the...
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