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The Effects of Temperature on the Function of Catecholase

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Liz Crawley Lab Group A-5 Nov. 12, 2002 The Effects of Temperature on the Function of Catecholase Introduction For this lab exercise, each group was assigned the task of choosing some aspect of enzyme function and studying it by designing an original experiment. Before choosing a specific aspect to study, all the lab groups did a general experiment to study the reaction rates of a specific enzyme, catecholase. Catecholase is an enzyme found in some many fruits and vegetables, and is responsible for the browning that occurs when a fruit is cut or damaged. Its substrate, catechol, reacts with oxygen in the air to produce water and benzoquinone. This is what has the reddish brown color. This experiment became the impetus for our decision as to what we wanted to study. When we compared our results to the results of the other groups in our lab section, we discovered that our results were unusually high. After discussing this for some time, we determined that the most probable reason for this is that one of the group members had held the test tube with the reaction occurring inside in her hands while waiting to use the spectrophotometer. The implementations of this were that we knew that this specific enzyme could work more efficiently at a higher temperature. ...read more.


Both our group and group A-4 tested 37 and 45 degrees. This allowed us to compare each group's results more accurately. The setup for the actual experiment was that each temperature had its own test tube rack. Four tubes of water and catechol and four tubes of enzyme were put into each rack, and these racks were then submerged into either a hot water bath or a circulating water bath, depending on which temperature was being tested. The tubes were allowed to sit in the water for approximately five minutes to allow the contents of the tubes to come up to the temperature we were trying to test. Then the tube of enzyme was poured into the tube of catechol, the tube was covered and inverted to mix the contents, and the timer was started. We allowed the reaction to run from three to five minutes, keeping track of exactly how long each set went for. Our method for ensuring that the reactions ran for the exact length of time stated was to start each reaction thirty seconds later than the first, and then take the measurements from the spectrophotometer exactly thirty seconds apart, keeping the tubes in the same order. Before measuring each tube, we again inverted it several times to make sure that the product was uniformly distributed throughout the tube. ...read more.


We also discovered after the experiment had been completed that the other group had left the catechol out in a separate tube during heating, while we left the enzyme out. This difference in method may have contributed to the differences. To make sure that these problems did not result in faulty conclusions, I looked up another experiment on the effects of temperature done by Pierre Greenway. Greenway's findings indicate that the peak temperature for enzyme function is actually at 40oC, and not 45. This is an interesting discovery, since we did not test thoroughly in the range of 37o-45o. The next course of experimentation suggested by these findings would be to thoroughly test the reaction rates at temperatures between 35 and 45 degrees Celsius. Measuring at one-degree intervals would give the best results, but may require another collaboration to be achieved in a reasonable amount of time. It may also be interesting to test the reaction rate at even higher temperatures, and try to find the point at which all of the enzyme is completely destroyed. According to the results of Greenway, this temperature was around 60oC for him, but we tested beyond that in our own experiment and found the rate to still be decreasing. Any of these questions would be interesting to try to answer. ?? ?? ?? ?? 1 ...read more.

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