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Enzyme Action: Testing Catalase Activity Enzymes are proteins that serve as catalysts and accelerate chemical reactions in living organisms. Enzymes accomplish this by lowering the energy of activation of the organism it is acting upon, however enzymes will only lower the energy of activation for specific organisms, reducing chaotic chemical reactions. The reaction is carried out in its entirety in the active site of the enzyme. The substrate (organism acted upon), binds itself into the active site, of the enzyme, and the chemical process begins. The enzymes active site will reform itself for the substrate in order to form a perfect bond, this is called induced fit. This is only one of the changes that could occur to accommodate the substrate.
For example, the enzyme might change the pH levels to promote the reaction. There are numerous factors that can affect the rate of the chemical changes, four have the greatest affect. They are the concentration of the enzyme, the temperature, the pH level, and the salt concentration. The higher the concentration of the enzyme the faster the rate of change there is upon the organism. The temperature affects the rate in this way; each enzyme has a specific temperature in which it functions at an optimum rate, too low of a temperature, the enzyme will not function at all. However too high of a temperature produces the same results.
Third, the pH level will affect the rate, H+ and OH- ions can cause the organism to change shape and become deformed, denature, and cause abnormal functionality. Finally, salt concentration will affect the rate of chemical change because the inorganic ions in salts will interfere with ionic bonds in protein molecules. There are very few factors that influence the function of the enzyme. Some enzymes require cofactors, substances that assist the chemical reaction.
Chemical inhibitors can inhibit the enzymes functionality (1) by attaching itself to the active site (competitive inhibitors) blocking the substrate; (2) by attaching itself to the enzyme in a place other than the active site, and changing the shape of the active site, thus disabling the active site. In this experiment, some of theses factors will be tested, concentration, heat, and pH levels. Much insight can be gained into their affects upon the rate of reaction. This experiment should show what the optimum concentration of the enzyme and pH level, and temp that is needed for the enzyme to perform at its peak rate. This experiment can be divided into three related sections, the testing of concentration, pH, and temperature. The concentration was first to be tested.
Four test tubes were labeled one to four respectively, and 3 ml of 3 % concentration H 202 was added to each. Test tube one received one drop of the enzyme, then was shaken for twenty seconds. The test tube was then plugged and the rate of reaction was tested by measuring the gas pressure inside the test tube for three minutes. Test tube two received two drops of the enzyme, once again shaken, then gas pressure was measured. This process was repeated for test tubes three and four, bot of which receiving three / four drops of the enzyme solution respectively.
The next section of the experiment tests the effect of temperature upon the rate of reaction. Once again, four test tubes were labeled (one to four); each receiving 3 ml of 3 % concentration H 202. A tub of water was cooled to a temperature between 0 - 5 Celsius. The first test tube containing 3 ml of H 202 was then dropped into the water to be cooled to this temperature also. Upon reacting the 0 - 5 Celsius temperature inside the test tube, two drops of the enzyme solution was added to the test tube, and shaken for twenty seconds.
Then the gas pressure was measured inside the test tube as before. This process was repeated for each of the remaining test tubes, except test tube two was measured at a temperature of 20 - 25 Celsius, test tube three was measured at 30 - 35 Celsius, and test tube four was measured at 50 - 55 Celsius. The final section of this experiment tested the effect of pH upon the organism. Three test tubes were labeled respectively, and 3 ml of 3 % concentration H 202 was added to each. Then, an additional substance was added to each of the test tubes, 3 ml of pH 4 (for test tube one), 3 ml of pH 7 (for test tube two), and 3 ml of pH 10 (for test tube three). Then two drops of the enzyme solution was added to the test tubes, shaken for twenty seconds as before, and once again the gas pressure was measured for three minutes.
This was repeated for test tubes two and three. Data that was collected for this experiment on the rate of chemical reactions is summarized in the following tables, and the graphs attached. Enzyme Concentration 1 drop 2 drops 3 drops 4 drops Rate of Reaction (atm / min Table 1 summarizes the rate of reaction of the enzyme upon the substance (H 202) by comparing different concentration levels of the enzyme, ranging from one to four drops. One can reach the conclusion that the higher the concentration, the higher the rate of reaction. Temperature Range (Degrees Celsius) Actual Temp.
In Test Tube (Degrees Celsius) Rate of Reaction (atm / min ) Table 2 summarizes the rate of reaction of the enzyme upon the substance (H 202) by comparing different temperature conditions of the enzyme, ranging from 0 to 55 Celsius. One can reach the conclusion that the optimum temperature of this enzyme is 30 - 35 Celsius. Each of the other temperature ranges produce results of either negative amounts or insufficient reaction rates. pH Buffer Level Reaction Rate (atm / min ) Table 3 summarizes the rate of reaction of the enzyme upon the substance (H 202) by comparing different pH levels the enzyme was exposed to, ranging from a pH of 4 to a pH of 10. One can reach the conclusion that the optimum pH level of this enzyme is a pH level of 10. The purpose of this experiment was to investigate the effects that enzyme concentration, temperature, and pH had on the rate at which enzyme catalyzed reactions took place.
The results of this experiment can be summarized as follows: This enzyme like others increases the rate of chemical change with an increase of concentration. This specific enzyme has an optimum temperature around 30 - 35 Celsius. Finally, the enzyme has an optimum pH level of 10. However we cannot assume that the higher pH level there is the higher the reaction rate. More tests with different pH levels would have to be performed.
This is the same case for the concentration of the enzyme, in order to say the enzyme functions better at a higher concentration more experiments with a higher concentration rate would have to be performed. For the time being, however it is safe to assume a steady increase in the rate of reaction with respect to an increase in concentration. A small amount of human error was included within this experiment, for example shaking (inadvertently) the test tube while gas pressure was being measured. However these errors werent significant enough to have influential effects on the overall results of these experiments. In conclusion, this experiment leads one to assume increasing enzyme concentration and pH continually, will increase reaction activity, and increasing the temperature will increase the reaction rate up until a certain point. Bibliography:
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