3.1 Apostolopoulos. The Effect of Cobalt Ions on the Activity of Catalase

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3.1 The Effect of Cobalt Ions on the Activity of Catalase

By Zoe Apostolopoulos ’22

Chapter 3. Life Science

Introduction:

Catalase is an antioxidant enzyme present in all aerobic organisms that catalyzes the reaction in which hydrogen peroxide (H2O2) is decomposed into water and oxygen. It is an extremely important enzyme because, without it, hydrogen peroxide could accumulate to toxic levels in certain cells and potentially be harmful or even deadly to the organism. We can determine if Extraterrestrius Martianii contains catalase by measuring the absorbance levels of H2O2 as the reaction progresses through spectrophotometer readings. We should expect to see a continuous regression in the concentration of H2O2 throughout the experiment as the enzyme catalyzes the reaction within the first few minutes of coming in contact with hydrogen peroxide. In the case of this experiment, cobalt ions are a known inhibitor of catalase, so we should expect to see some inhibition of its activity through higher concentrations of H2O2. Therefore, if it is determined that Extraterrestrius Martianii contains catalase, then the addition of cobalt ions will decrease the enzyme’s activity, producing a greater concentration of H2O2 (M) throughout the entirety of the reaction.

Measuring Catalase Activity:

Catalase activity was measured through a spectrophotometer which measures light absorption. After the progression of the catalyzed reaction was observed at 30second intervals ranging from 0-3 minutes, a few minutes were allowed for the color to develop before transferring the different samples into cuvettes. The cuvettes were then individually placed in the spectrophotometer where their wavelengths (or colors) were determined. The earlier in the reaction, the greater the absorbance level and the darker the color will be. The farther in the reaction, the lower the absorbance level and the lighter the color will be. Results:

In the graph above, we see the concentration of H2O2 (M) produced in Trial 1 and Trial 2 over the course of 3 minutes. Both trials follow a similar line of regression with the highest concentration levels of H2O2 at 0 minutes. Overall, Trial 2 had great concentrations of H2O2 throughout the entirety of the reaction compared to Trial 1.

Discussion:

The clear linear regression relationship between the concentration of H2O2 and the time allotted for the reaction to occur proves that Extraterrestrius Martianii contains catalase. The highest concentrations of H2O2 were recorded at 0 minutes because the catalase had not had time to initiate the catalysis of the reaction, leaving a 100% concentration of H2O2. The following regressing points at each 30-second interval prove the activity of catalase, as the more time the enzyme is given to react, the greater the reduction of H2O2 will be. Furthermore, the data from Trial 2 consistently displays a greater concentration of H2O2 at each 30-second interval compared to the data from Trial 1. This greater concentration of H2O2 throughout Trial 2 supports the hypothesis that the addition of cobalt ions will decrease the enzyme’s activity, therefore producing a greater concentration of H2O2 (M) throughout the entirety of the reaction, given that the cobalt ions are the only variable that changed from Trial 1 to Trial 2.