Enzyme Lab Report - pH Essay Example

Abstract:
An enzyme is a protein that serves as a biological catalyst (Denniston, 2007). Metabolic reactions happen with in cells. Enzymes are proteins that are used to speed up these reactions without being consumed by them (Mader, 2010). Catalase is a catalyst that digests potent hydrogen peroxide and converts it into H2O and O (Campbell Reese, 2008). The environment plays an important role in the reaction that enzymes have. In this experiment, enzymes were exposed to changes in temperature, pH, and concentration.

Introduction
In this experiment, the environment of the enzyme was altered, by increasing or decreasing the temperature, pH and concentration. The purpose was to observe if and how the enzyme would react to such changes. This experiment tested whether heating or cooling a catalase would increase or decrease the rate of reaction. The temperature was increased by placing the test tube in boiling water to test if the enzyme would begin to denature and break down, causing less of a reaction. The temperature was also decreased by placing the test tube in a refrigerator to test if the enzyme would slow down and the reaction would be minimal or it would cease. Altering the pH would cause denaturing of the enzymes and slow its reaction rate to almost non-existent. Increasing the concentration of catalase, you will see a correlation in the increase of the reaction.

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Material
• Potato
• 250mL Beaker
• Four 100mm test tubes
• Mortar and Pestle
• Refrigerator
• Hydrogen Peroxide
• 7.0 pH Phosphate buffer solution
• Thermometer
Methods
The potato was crushed with a mortar and pestle to make a slurry (the catalase) and poured it into a 250 ml beaker. Four 100 mm test tubes (marked at every cm) were filled from the beaker with a mixture of the catalase and a 7.0 pH phosphate buffer solution to the 1 cm mark on each of the test tubes. One test tube was placed in the refrigerator at 7°C, one in the incubator at 37°C, one in boiling water at 100°C, and one was left at room temp (23°C). After 15 minutes, remove the test tubes one at a time and 2 cm of hydrogen peroxide were added to each and then swirled for approximately fifteen seconds. Twenty seconds after swirling the height of the bubble column was measured and recorded.

For the second test, the concentration of the peroxide to catalase ratio was changed, leaving the temperature and amount of hydrogen peroxide as constants. Three test tubes (all marked at every cm) were used. In the first tube, 1cm of catalase mixture with 4cm of hydrogen peroxide was added. The second tube contained 2cm of catalase with 4cm of hydrogen peroxide was added and the third was added, 3cm of catalase with 4cm of hydrogen peroxide. The height of the bubble column was recorded for each.

For the third test, the pH of each solution was altered, keeping the concentration and temperature constant. Three separate test tubes (all marked at every cm) were filled, each starting with 1cm of catalase. 2cm of hydrochloric acid was added to one tube, with a pH of 3. Test tube two was left neutral adding 2cm of a 7.0 phosphate buffer, and to the third test tube was added 2cm of sodium hydroxide with a pH of 11. 4cm of hydrogen peroxide was added to all three tubes. They were swirled for approximately fifteen seconds. After that, the height of the bubble column was recorded.

Results
For our first test, the height of the bubble column was recorded as a reaction to the enzyme and temperature change. The following results were obtained. The test tube that was placed in the incubator (37°C) had 10mm of bubble height. The test tube that was left at room temperature (22°C) had a small reaction with 5 mm of bubble height. The test tube that was in the refrigerator (7°C) had the largest reaction with 15 mm of bubble height. The test tube that was in boiling water (100°C) had no reaction. By increasing the temperature, the catalase would begin to denature and have a very minimal reaction. The cold temperature would slow down or stop the reaction. For our second test, the amount of catalase concentration was increased. The following results were obtained. Test tube one was 1 cm to 5 cm with the bubble height measured at 50 mm. Test tube two was 2 cm to 6 cm with the bubble height measured at 30 mm. Test tube three was 3 cm to 7 cm with the bubble height measured at 70 mm. For the third test the pH increased and decreased. The following results were obtained. With a pH of 2, test tube one had no reaction. With a pH of 7 the height of the bubble column was measured at 30 mm. With a pH of 11 test tube three had no reaction. We concluded that the closer the pH is to neutral the more of a reaction will occur.

Test One:
Trial 1
Incubator (37°C) 10mm
Fridge (7°C) 15mm
Boiling (100°C) 0mm
Room Temp (22°) 5mm

Trial 2
Incubator (37°C) 15mm
Fridge (7°C) 20mm
Boiling (100°C) 0mm
Room Temp (22°) 5mm

Test Two:
1cm-5cm 50mm
2cm-6cm 30mm
3cm-7cm 70mm

Test Three:
pH 3 0mm
pH 7 30mm
pH 11 0mm

[pic]
Figure 5.2 (above) shows the effect temperature has on enzyme activity. The temperature is measured in Celsius and enzyme activity is measured in bubble height in millimeters (mm). The different settings of temperature were The Refrigerator at 7 degrees Celsius, Incubator at 37 degrees Celsius, in boiling water at 100 degrees Celsius and in room temperature at 22 degrees Celsius. The bubble height are as follows the refrigerator at 20mm, Incubator at 50mm, Boiling water at 0 mm, and at room temperature activity rose to 50mm.

[pic]
Figure 5.3 shows the amount of enzyme. We measured the amount of enzyme in centimeters (cm) and bubble height in millimeters (mm). The amount of enzyme are in ranges as follows: tube 1 1cm-5cm, tube 2: 2cm- 6cm, and tube 3: 3cm -7cm. The bubble height follows: tube 1: 50mm, tube 2: 90mm, and tube 3: 100mm.

[pic]
Figure 5.4 shows the effect different pH levels have on enzyme activity. We tested to see if the pH levels have any effect on the activity of enzymes. Tube 1 had a pH of 3 and there was no effect of activity. Tube 2 had a pH of 7 and the activity in this particular on was a bubble height of 30(mm). Lastly we tested tube 3 with a pH of 11 and there is no activity going on. The graph will show these changes in activity. Overall the data tells us that neither acidic or basic pH levels cause a change, but the exception would be a moderate level would cause some change. Discussion

The temperature increases or decreases the reaction of an enzyme. pH also plays an important role in enzyme reactions. The closer the pH is to neutral, the more of a reaction will occur. Increased temperatures increased the reaction rate until reaching higher temperatures where the rate of reaction slowed down due to the denaturation of the enzyme. Enzymes only function within specific pH levels and the optimal level was found to be eight. Increased concentration of enzymes increased the rate of reaction until the concentration is higher than that of the substrate where the substrate became a limiting factor. Increased concentration of substrate increased the rate of reaction until the concentration was too high and the enzymes were at maximum velocity, which caused the rate of reaction to not increase any further.

References:
Bennett, T. P., and Frieden, E.: Modern Topics in Biochemistry, pg. 43-45, Macmillan, London (1969). Campbell, N. A. (2008). Biology. San Francisco: Pearson Benjamin Cummings. Holum, J.: Elements of General and Biological Chemistry, 2nd ed., 377, Wiley, NY (1968). Mader, S. S. (2010). Laboratory Manual. New York: Mc-Graw Hill. Martinek, R.: Practical Clinical Enzymology: J. Am. Med. Tech., 31, 162 (1969). Harrow, B., and Mazur, A.: Textbook of Biochemistry, 109, Saunders, Philadelphia (1958). Pfeiffer, J.: Enzymes, the Physics and Chemistry of Life, pg 171-173, Simon and Schuster, NY (1954)

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