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Effects of Temperature on Catalase Activity

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Effects of Temperature on Catalase Activity

Effects of Temperature and pH on Catalase Activity


Enzymes are organic catalysts that spur metabolic reactions. The presence of an enzyme within a cell is essential in order for any sort of reaction to take place. All enzymes are complex proteins that act in an organism’s closely controlled internal environment. In such a homeostatic environment, the temperature and the pH (concentration of hydrogen ions), remain within a fairly narrow range. Extreme variations in pH and temperature denature the enzyme by altering its chemical structure, thus adversely affecting the chemical reaction. As even the slightest change in the protein’s structure will change the enzyme’s shape enough to prevent the formation of the enzyme-substrate complex, the reaction will then be unable to take place. The enzyme, catalase, reacts with hydrogen peroxide in order to yield water and oxygen. Therefore, upon reaction, bubbling will occur as oxygen is produced. The amount of bubbling, or oxygen that is produced is dependent on the conditions under which the reaction takes place (or fails to).


The Purpose of this experiment was to determine the optimal temperature and pH levels under which enzymatic reactions involving the enzyme catalase and the reactant, hydrogen peroxide, may successfully occur.


It is hypothesized that because extreme variations in temperature and pH will negatively affect the reaction, mild temperatures and more neutral ph levels will yield the best results (most bubbles).


In order to conduct the tests on temperature and pH, 8 test tubes were used; five for temperature, and three for pH. Upon preparation for the tests, the three temperature test tubes were marked at the 1 cm and 5 cm levels, while the three pH test tubes were marked at the 1, 3, and 7 cm levels. To test for temperature, each tube was placed in a separate location with varying temperature: a refrigerator (5 degrees), an incubator (32 degrees), Boiling water (99 degrees),a warm bath (22 degrees), and a hot bath (85 degrees). After placing each tube in its experimental setting, 15 minutes elapsed before removing them. Immediately after removing the tubes, hydrogen peroxide was added to each tube up to the second (5 cm) mark. They were then swirled to mix, and after fifteen seconds, the bubble columns in each vile were measured in millimeters, and then recorded in a data table. The procedure for analyzing pH levels was rather different. The three test tubes, marked at three different levels, were each filled to the first mark (1cm) with catalase, and to the second mark (3 cm) with water. However, the pH of the water had been adjusted differently for each vile. The first tube received water adjusted to pH three, the second received water adjusted to pH seven, and third received pH eleven. Consequently, each tube was then filled to the last mark (7 cm) with hydrogen peroxide, swirled to mix and then observed after twenty seconds. After twenty seconds passed, the bubble columns of each of he tubes were measured in millimeters. Results were recorded on a chart.


As expected, during the temperature test, the least amount of bubbles were emitted in tubes that had been exposed to extreme heat. The tube placed in boiling water yielded zero millimeters of bubbles. The boiling water denatured the enzyme and altered its chemical structure rendering it incapable of undergoing metabolic reactions. For these same reasons, the vile placed in a hot bath, containing water at 85 degrees,

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