Running head: THE EFFECTS OF PH ON CATALASE ACTIVITY

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The Effects of pH on Catalase Activity

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Class XXXX, Section XXXX, Fall 2011

THE EFFECTS OF PH ON CATALASE ACTIVITY

Abstract

This study examined the effects of pH on catalase activity obtained from research

conducted in laboratory. The aim of an experiment was to discover the level of pH at which

catalase functions most effectively. In this experiment potato extract and a buffer with the

appropriate pH were liquefied together and hydrogen peroxide was added, in order to test

measure the rate of enzyme activity at different pH levels. Foaming was indication of enzyme

activity. Together, these findings suggest that catalase functions better in a neutral pH than it

does in either an alkaline or acidic pH level.

Keywords: catalase activity, pH, hydrogen peroxide, foaming

THE EFFECTS OF PH ON CATALASE ACTIVITY

The Effects of pH on Catalase Activity

While researching mechanism of action of catalase it was found that catalase is an

enzyme that detoxifies hydrogen peroxide, and other similar byproducts, into water and oxygen.

(Cornwell W., 1999). This experiment is important by the reason mankind have catalase, which

helps to protect our cells from damage done by toxic chemicals in our bodies. The catalase in the

human body functions best at a specific pH (Cornwell W., 1999). According to numerous

literature sources which states that when catalase breaks H202 into H2O and O2, oxygen bubbles

in the form of foam is produced as follows (www. biology.kenyon.edu):

2 H2O2 2 H2O + O2

When looking at a measure the effects of changes in pH on rates of an enzyme-catalyzed

reaction in a controlled experiment, it is crucial to set up the following objectives for the study:

1. To explore carefully effect of pH (concentration of Hydrogen ions) on the enzyme

catalase (potato extract) and to note the reaction, if any, when hydrogen peroxide is added.

To achieve this goal, it is important to better understand what pH is. Analyzed numerous

literature sources it was found that pH is a logarithmic scale that measures the acidity or H+

concentration in a solution. Thus, it is plausible that when the pH is in the range of fewer than 7,

a solution is said to be acidic; if the pH is 7, the solution is neutral: and if the pH is in the range

of over 7, the solution is basic (www.science-projects.com).

Method

Potato extract was used in the experiment because this plant contains catalase.

Experiment was started with 5 test tubes marked at the 1cm, 2cm and 5cm line. 5 different pH

levels were tested: pH level 2,5,7,10,12. Potato extract was placed in each test tube. Then was

added 1cm of a buffer with the appropriate pH to each tube: tube 1 had a pH of 2 and tube 2 had

THE EFFECTS OF PH ON CATALASE ACTIVITY

a pH of 5 and so forth. Then 3cm hydrogen peroxide (H2O2) was added to each tube. When 30

seconds was passed the foam in each tube was measured using a ruler. Results were charted,

compared and evaluated.

Results

We have clearly identified above that there is should be a relation between pH and

enzyme activity. In order to establish this relation we need to build a diagram which illustrates

the foaming dependence on pH level.

Analyzing created diagram (see Figure 1) it was noticed that at a pH of 2 and 12 it had

approximately 20mm of foam and no significant effect was observed. We also note that at pH 5

and 10 it had approximately 40mm of foam. What is more important at this stage is that at pH 7

it had 80mm of foam which showed the greatest reaction meaning the enzyme catalyzed reaction

was greater at pH 7. This indicates that it had the optimum pH and the enzyme was most active

and consequently catalase is functioning at more efficient level. The high and low concentration

of hydrogen ions caused enzyme to denature.

Figure 1.

0

10

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90

2 5 7 10 12

Foam height, mm

pH Level

Foam height

THE EFFECTS OF PH ON CATALASE ACTIVITY

Summary

The purpose of this study was to test the effect of pH on enzyme activity. We predicted

that there is a definite difference in the functioning of catalase at various pH levels. Based on

empirical evidence and our data analysis shown above we can suggest that it is clear that acidic

or alkaline pH inhibits the enzyme activity of catalase as well as a neutral pH is an optimum

environment for the catalyst to disintegrate peroxide. Taken together, these findings we can

conclude that catalase functions better in a neutral pH environment.

THE EFFECTS OF PH ON CATALASE ACTIVITY

References

Boon E. M., Downs A, Marcey D. Proposed Mechanism of Catalase. Catalase: H2O2:

H2O2 Oxidoreductase: Catalase Structural Tutorial. Retrieved Oct 04, 2012 from

http://biology.kenyon.edu/BMB/Chime/catalase/frames/cattx.htm#Proposed%20Mechanism%20

of%20Catalase

Cornwell W. (1999). Discovering the Effects of pH on Catalase in Purple Cabbage.

Retrived Oct 04, 2012 from http://biology.clc.uc.edu/students/114-fall99/Catalase.htm.

Catalase kinetics. The determination of various biochemical and biophysical constants for

this enzyme. Retrieved Oct 04, 2012 from http://www.science-projects.com/catalasekinetics.htm.