The Relationship between Catalase and Chemical Reactivity
 
Introduction
Enzymes are naturally occurring proteins in living organisms, which are essential for survival. Enzymes are specific in nature and functionality, e.g. breaking down food. Their function entails catalyzing the chemical reaction by providing impetus to the reactants. The enzyme employed for carrying out the experiment is catalase. The essential component of hydrogen peroxide breakdown in organisms is catalase. Hydrogen peroxide, H2O2, is a toxic substance that can annihilate cells. Nevertheless, H2O2 is engendered as a byproduct of cellular reactions. To get rid of the noxious compound, the human body specifically produces catalase, which turns H2O2 into water and oxygen. The equation for the reaction is as follows:
2H2O2                    2H2O + 2O2
The decomposition process is fastened in the presence of catalase as the activation energy of H2O2 is lowered, without consumption of the enzyme. The purpose of investigating the relationship between substrate concentration and reactivity is fulfilled by measurement of pressure change with time. Higher reactivity will produce more oxygen and pressure increase. Thus, by examination of pressure change over time, the rate of reaction will be analyzed.
 
 
Design
Research Question. What is the effect of enzymatic concentration increase on the rate of reactivity of the chemical reaction?
Hypothesis. The increase in enzyme concentration will accelerate the rate of reaction, as the availability of enzyme and contact area for reaction with the component increases. The claimed hypothesis will manifest if all the other parameters including temperature, pH of the environment, and inhibition factors are kept constant.
 
Variables
Independent Variable: The volume of liver – containing catalase and hydrogen peroxide used in the experiment.
Dependent Variable: The concentration of oxygen produced by the reaction of hydrogen peroxide with liver containing catalase.
Controlled Variables: Variations control the mass of liver specimen, containing the catalase enzyme, obtained for the experiment. The volume of solution used is also controlled, as the same amount is used in all trials. The temperature is kept constant in all trials. Usage of only one method for conducting the analysis controls the procedure of experiment.
 
Materials

Beaker (250 ml)
Plastic bottle (250 ml)
Liver cubes from Ovis Aeries (each cube is 5 g)
Data Logger
H2O2 (20 moles/dm3)
Tweezers
Oxygen gas sensor machine

 
Safety Measures
Gloves and a laboratory coat should be worn at all times to avoid contact with hydrogen peroxide, which is corrosive to human skin. Tweezers should be used to place the liver inside the hydrogen peroxide.
 
Procedure

Thoroughly disinfect the surface of all materials in contact with the raw liver so that it does not get contaminated.
Turn the data logger on and put one piece of liver sample weighing 5 grams onto the tray, with the help of tweezers.
Drop hydrogen peroxide in the form of droplets. The amount of H2O2 should be 100ml with 20% concentration.
Completely seal the apparatus of the data logger.
The data logger is turned on for the duration of 5 minutes.
After completion of the first trial, results are checked and tabulated.
Data logger measures the concentration of oxygen produced, in parts per million (ppm).
A second trial is conducted with 10 grams of liver, i.e. two pieces of liver.
The process is repeated for 5 minutes in the data logger.
The data logger measures the concentration of oxygen produced, and the results are observed.

 
Data Collection and Processing
Qualitative Data

Mass of Liver in grams
Volume of Oxygen Produced (ppm)
T1                                                  T2                             T3                  Average

5 grams
4270
4324
5732
4775.3

10 grams
4440
4416
6545
5133.6

Table 1: Concentration of Oxygen released from the reaction
 
Overview
The table shows the entries of 3 trials held for the two variable values of liver mass. The average values give an idea of how concentration affects the release of oxygen due to an elevation in the rate of reaction.
 
Sample Calculation
By summing the values of all trials and finding the average by division with 3, we find the average concentration release for both masses.
Rate of Reaction
Ppm
Similarly, Rate of Reaction, RR2, for the second specimen is 5133.6 ppm.
 
Conclusion and Evaluation
The data can be interpreted by plotting a graph between the two variables i.e. oxygen released and the amount of liver mass utilized.
Graph 1: Number of trials versus concentration graph
 
The data collected and the graph indicate that the hypothesis is correct. The production of oxygen increases when the amount of liver catalase is increased. Catalase breaks down the hydrogen peroxide introduced into the controlled environment. The graph assumes a steeper slope in case of the second experiment, where oxygen concentration and catalase are both increased in the experiment.
The limitations of this experiment lies in any inconsistency in placing the correct amount of catalase in the data logger or variation in the introduction of H2O2. This might induce disparities in the results. Contamination can also lead to inaccuracy in the result. Poor calibration of the data logger can also yield discrepancies in the results.
Sterilization of the equipment can engender accurate results. Proper calibration of the apparatus will lead to precision in results.
References
Williams, J. “The Decomposition of Hydrogen Peroxide by Liver Catalase”. Journal of General Physiology, vol. 11, no. 4, pp. 309-337.
George, P. “The Effect of the Peroxide Concentration and Other Factors on the Decomposition of Hydrogen Peroxide by Catalase”. Biochemistry Journal, vol. 44, 1948, pp. 197-205.
Northrop J.H. “The Kinetics of the Decomposition of Peroxide by Catalase”. Journal of General Physiology, vol. 7, no. 3, pp. 373-387.
Science B. “The Liver: Helping Enzymes Help You”. Scientific American, 8 March 2012.
Aebi, H. “Catalase in vitro”. Methods in Enzymology, vol. 105, 1984, pp. 121-126.

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