Enzyme Lab

Purpose: The purpose of this experiment was to find how much of the hydrogen peroxide decomposes depending how how long the enzyme was able to react with the catalase extract. In shorter terms, we trying to figure out how much product an enzyme could make during a certain time period. 

Introduction: Enzymes, which are made out if proteins, speed up chemical reactions inside a cell; another word to describe an enzyme is a cataylst. When a substrate is added to this enzyme-catalyzed reaction, the energy needed for the reaction to occur is reduced. At any point in a reaction an enzyme-catalyzed reaction could stop if there is a change in pH, temperature, or salt concentration. Sometimes the enzyme-catalyzed reactions can be completed changed due to activators or inhibitors which can change the shape of the enzyme or block certain substrates of going into the active site. 

Methods, Charts, and Graphs: in order to have a baseline of how much unreacted hydrogen peroxide is in 5 mL of  1.5% Hydrogen peroxide, we put 5 ml of unreacted hydrogen peroxide in a cup and titrated it with KMnO4. For the baseline, 3.6 mL of KMnO4 were used. To find how much Hydrogen peroxide is catalyzed over different periods of time, we added yeast, which contains catalase, into the hydrogen peroxide, and let it react for specific times. After he time was up, we added sulfuric acid to denature the enzyme, stopping the reaction. We then took 5 mL of the catalyzed hydrogen peroxide, and titrated it with KMnO4 to see how much hydrogen peroxide was left. We subtracted that number from the baseline to find how much hydrogen peroxide was broken down by the catalase.

Here is the data table that shows how much KMnO2 is consume and H2O2 is used.

Here is a graph showing the amount of H2O2 is used up over time.

Discussion Questions:

     The rate of reaction is highest for the longest time period, 360 seconds, because the catalase has had more time to break apart the H2O2. The lowest rate was the lowest time period, because it hadn't had as much time to react. We stopped the reaction with H2SO4, an acid that denatured the catalase, and as a result, it could no longer break apart the H2O2. Lowering the temperature would also inhibit the reaction, as temperature changes can also denature an enzyme. Enzymes have an optimal pH and temperature, and under these conditions the rate of reaction is highest. An experiment to determine this would be to measure the rate of reaction with the time and temperature held constant, at different pH, and again with time and pH held constant, at different temperatures.

This shows how the pH of an enzyme relates to how efficient proteins can function.