Effects of environmental factors on the rate of enzyme catalyzed reactions
Guangyu Qi & Xiaoxi Yue
Professor Sahil Wadhwa
22th February 2019
· Introduction
In this report, we will mainly talk about what affect the rate of enzyme catalyzed reactions by discussing two experiments, that are experiment-effect of temperature on enzyme-catalyzed reactions and experiment-effect of PH on enzyme-catalyzed reactions. Why is enzyme so important that deserve us to do experiments on it? In living organisms, there is a class of substances that promote metabolism and promote the smooth progress of all life-related chemical reaction, which is enzyme. There is a very large family of enzymes. There are about 2,000 kinds of enzymes known at present, and there are more than 700 kinds in the human body. They are spread all over the human mouth, gastrointestinal tract, pancreas, liver, muscles and skin. In a word, we can’t live without the using of enzymes. Therefore, it’s necessary for us to figure out what factors affect such important enzymes, and how our enzymes affected by those factors.
Moreover, we will use a machine called Spectrophotometer (Spec 20) in two experiments. The reason why we use Spec 20 to compare the rate of the reaction under different conditions is that the Spec 20 is a device that measures how “dark” a liquid is, as more and more (clear) catechol is converted to (brown) benzoquinone, less and less light will be able to pass through the test tube, and the percentage of light absorbed will increase. Therefore, Spec 20 is the best choice for these two experiments.
Hypothesis:
As a substance produced by a living organism and acts as a catalyst to bring about a specific biochemical reaction. In the experiment-effect of temperature on enzyme-catalyzed reactions, we hypothesized that enzymes are most efficient at appropriate temperature like 30°C and 40°C. For example, in our daily lives, when our body have high fever or low fever, we will feel extreme discomfort; thus, we hypothesized high temperature or low temperature will affect the efficiency of enzymes.
In the experiment-effect of PH on enzyme-catalyzed reactions, we hypothesized that the rate of an enzyme catalyzed reactions is greatest at pH values that are 7. For instance, the most indispensable and needed substance in our body is water, which is typical neutral liquid in nature; thus, we hypothesized acid and base condition will affect the efficiency of enzymes.
Effect of temperature on enzyme-catalyzed reactions
Materials
1. 6 test tubes with a test tube rack,
2. a wax pencil,
3. a pipette,
4. 5 different water bathes (Ice 0, room temperature, 30,40,60) and
6. potato extract,
7. water
8. catechol.
Method
1. We use a wax pencil to mark the tubes with numbers 1 through 5 and “X” and leave the last tube as “blank”.
2. We measure 1 ml of potato extract (a rich source of the enzyme catechol and 4 ml of water into each of the 5 tubes with a pipette.
3. To make a “blank,” we put 1 ml potato extract and 6 ml of water into the sixth tube. And we cover all 6 tubes with parafilm, invert to mix, and stand the tubes in rack.
4. We separate 5 tubes into different 5 water bathes and take 5 minutes to make sure the temperature of the solution inside our test tubes have reached the temperature of its water bath.
5. We add 2 ml of catechol solution to each of the 5 sample tubes simultaneously in the same sequence, so that reaction times in the 5 samples will be comparable. We remove the tube from the water bath, remove the parafilm, add the catechol, put the parafilm back on, and invert tube to mix the contents. Return each tube to its bath for 5 minutes.
6. We use the blank to recalibrate the Spec 20.
7. Exactly 5 minutes after adding the catechol, remove each sample tube from its water bath, dry it, insert the tube into the sample holder of the Spec 20, and measure absorbance. Quickly repeat for the other 4 tubes, one at a time, in numerical order. Record these values.