DIFFERENCES OF SUBSTRATE CONCENTRATION By: Naomi Belcher, Julia Calhoun, Rayvin Ewers, and Katarina Mayer

Abstract This experiment was posed to find that if a higher concentration of substrate was added to a solution with a constant concentration of enzyme. In this case catalase was the enzyme and hydrogen peroxide (H2O2) was the substrate. To do this, water (H2O) and different concentrations of H2O2 were put into four test tubes and a drop of the enzyme catalase was added and then the rate of reaction was measured by a pressure sensor. As the concentration of the H2O2 increased, the slope of each line was supposed to increase, but technological difficulties prevented this from being collected. Barring complications, this experiment turned out to prove our hypothesis correct because when the higher concentration of H2O2 was added, the rate of reaction increased.

Background ■GOAL –To determine whether or not catalyze speeds up or slows down a enzymatic reaction ■Researching the experiment we found that, the reaction begins very swiftly. As soon as the enzyme and substrate are mixed, bubbles of oxygen are released quickly. A large volume of oxygen is collected in the first minute of the reaction. As the reaction continues, however, the rate at which oxygen is released gradually slows down. The reaction gets slower and slower, until it eventually stops completely.

Hypothesis When there is a higher amount of substrate concentration, the rate of reactions will be higher than the reactions that took place with a lower amount of substrate concentration.

Materials and Methods ■Test tubes: 4 ■Beakers: 5 ■Different concentrations of H2O2: 3 ■H2O ■Safety equipment ■Pipettes ■Vernier gas pressure sensor ■Logger Pro software ■Vernier LabQuest Mini ■Stand for test tubes ■Computer ■Labeling equipment ■Catalase concentration of 200 units/mL

Materials and Methods 1. Put on safety equipment 2.Gather all the materials that are listed above 3.Hook up the Vernier LabQuest Mini and the Vernier Gas Pressure Sensor together and then up to the computer that has the LoggerPro software downloaded and pulled up 4.Put all four test tubes in the test tube stand and label them 1, 2, 3, and 4 5.Put all solutions (H2O, all concentrations of H2O2, and catalase) in separate beakers 6.Add 3 mL of H2O to each of the 4 test tubes in the rack 7.Add 3 mL of 1.5% H2O2 solution to test tube 2 8.Add 3 mL of 3% H2O2 solution to test tube 3 9.Add 3 mL of 6% H2O2 solution to test tube 4 10.Add one drop of catalase solution to test tube 1 and put the stopper into the test tube and hit collect on the Logger Pro Software 11.Collect the data for 200 seconds while agitating the tube during collection 12.Repeat steps 10 and 11 for test tubes 2, 3, and 4

Results The result of our experiment is that the concentration of the substrate does affect the oxygen that is produced. Our substrate was H2O2, we used the concentrations of 6%, 3%, and 1.5%. The highest concentration, 6%, had the highest rate of kPa/s produced. The lowest concentration, 1.5%, had the lowest rate of kPa/s produced. All are shown in Figure 1 and 2. The higher the concentration of H2O2, the steeper the slope of the graph should have been.

Discussion The results of the experiment coincide with the hypothesis. We predicted that the more catalyze, the faster the enzymatic reaction. Also we observed downfalls in the experiment: our gas pressure sensor didn’t work accurately, the Logger Pro stopped working, the computer died, and the catalase aged. Even with mix of all the disruptive occurrences, the reading still came out positively. The improvements that could be made are check all the equipment before and make sure they work before starting, do all runs of the experiment in one day so the catalase doesn’t go bad, and go through more experimental runs for more accurate results.

Conclusion ■In this experiment we have learned that the substrate concentration does effect the oxygen produced by the catalase. –Catalase is an enzyme found in living organisms that changes hydrogen peroxide (H2O2) into water and oxygen. ■When the substrate concentration was at the highest of 6%, more oxygen was produced by the catalase. Less oxygen was produced when the lowest substrate concentration of 1.5% was used. ■ So, as the concentration of the substrate increases so does the enzymatic reaction.