Catalase Lab Report

An enzyme is a tertiary globular protein. The function of an enzyme is to lower the activation energy of either the creation or breaking apart of a chemical bond. By lowering the activation energy of this process, the reaction of bonding, or in this case breaking apart, is sped up. An enzyme breaks apart the substrate in the active site of the enzyme; this is where the magic happens. Substrate is what is being broken apart by the enzyme. In this case, the enzyme is catalase and the substrate is hydrogen peroxide, or 2H2O2.

As the catalase and the substrate interact, the substrate is brought into the catalase and broken apart into water and oxygen. This process may be able to happen naturally, but the enzyme, catalase, speeds up the process. It does so by bringing a molecule into it's active site and shifting it's own shape to put strain on the bonds. The structure of the hydrogen peroxide is 2H2O2 and is broken down to 2H2O + O2. When the piece of filter paper is dipped into the catalase and dropped into the substrate, bubbles appear and the paper sinks briefly and floats back into the top. A higher enzyme concentration to break the substrate apart, or a smaller ammount of substrate should speed up this process.

From our previous data collected about how enzymes work and what they should do, a couple of major things should happen in this experiment. As long as there is some substrate and some catalase present, bubbles should appear in the vials because oxygen is a product of the reaction. Secondly, the process of the substrate breaking up should speed up with higher catalase concentration and/or with lower substrate concentration. As enzyme concentration goes up, a faster rate of reaction is expected because there are more enzymes to do the work. As substrate concentration goes up, a slower rate of reaction is expected because there is more substrate to do work on. As temperature goes up, a faster rate of reaction is expected because heat adds energy, which should lower the activation energy even more.

Because hydrogen peroxide is being used in this lab, safety precautions like wearing eye protection were taken seriously. For the first group of tests, 5 vials containing 8 ml of 3% hydrogen peroxide, 5 different concentrations of catalase including 0 units/ml, 20 units/ml, 50 units/ml, 80 units/ml, and 100 units/ml, forceps, a ruler, and a dropper were used. For the second group of tests, 1 vial containing catalase at 100 units/ml, 5 vials containing different concentrations of substrate (hydrogen peroxide) including 3% H2O2, 1.5% H2O2, .75% H2O2, .38% H2O2, and 0% H2O2, forceps, a ruler, and a dropper were used. For the final group of tests, 4 test tubes containing 2 ml of catalase at 100 units/ml, 4 vials containing 8 ml of 3% hydrogen peroxide, 3 water baths at 0 degrees celsius, 37 degrees celsius, and 100 degrees celsius, forceps, a ruler, and a dropper were used.

In the first test, the effect of enzyme concentration on enzyme activity was tested. To begin the test, a piece of filter paper was dipped into the 100 units/ml catalase solution using forceps and dried out on a paper towel. While the paper drained, the first test tube was measured from the bottom to the top of the substrate. The drained filter was then dropped into a vial of 8 ml 3% H2O2. The distance traveled and the time was then recorded in the data chart. This process was repeated for each other enzyme solution with a fresh vial of substrate for each solution.

In the second test, the effect of substrate concentration on enzyme activity was tested. To begin this test, a piece of filter paper was dipped into a vial of catalase at 100 units/ml using forceps and dried out on a paper towel. While the filter drained, the first test tube was measured from the bottom to the top of the substrate. The drained filter was then dropped into a vial of 3% H2O2. The distance traveled and the time was then recorded in the data chart. This process was repeated for each of the other substrate solutions.

In the third and final test, the effect of temperature on enzyme activity was tested. To begin this test, 3 water baths were set up. One bath was cooled to 0 degrees celsius, one was heated to 37 degrees celsius, and one was boiled to 100 degrees celsius.