December 19, 2016
Catalyze student learning in AP*® Biology through an investigation of enzyme activity. By using a PASCO Wireless Spectrometer students can monitor the reaction in real-time and build a more robust data set.
Students can investigate the decomposition of hydrogen peroxide into water and oxygen by using peroxidase (found in filtered turnip extract). With a small amount of Guaiacol in solution the reaction can be easily monitored in the Wireless Spectrometer because it changes color as it oxidizes.
After creating a blank and calibrating the Wireless Spectrometer on the Analyze Solution tab, select the target analysis wavelength of 470nm.
Figure 1. Setting the analysis wavelength in the Spectrometer Software
Students can then go to the Time tab to monitor the reaction at 470nm. Prepare the reaction in a standard cuvette by adding the substrate (H2O2), pH buffer, and Guaiacol. Once the enzyme extract is added the reaction proceeds quickly, so make sure to test the reaction before the lab and dilute the enzyme extract if needed.
Figure 2. Monitor the reaction in real time before analyzing and comparing runs from various trial groups
After establishing a baseline, the rest is inquiry! By changing the pH buffer, temperature, or enzyme and substrate concentrations students can quickly explore the reaction and identify the optimal conditions for turnip peroxidase. Data can be analyzed in the software to determine the rate of reaction or exported for aggregation and further analysis. This is a great lab to introduce or reinforce concepts around protein structure and specific nature of the enzyme-substrate complex. Students can also compare the catalyzed and uncatalyzed reaction to see how the energy of activation is lowered by these (seemingly magic) biological molecules!
Figure 3. Sample data from investigation of Peroxidase reaction at pH 2, 4, 7, 10, 12
* AP is a registered trademark of the College Board, which was not involved in the production of, and does not endorse, this product or activity.