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Peroxidase Enzyme Biology Lab Report (Half Way Finished)

How Enzymes Work In Different Environments By Sarah Smith Biology1111 October 20, 2011 Lab Partner: Nellie Greer ABSTRACT Peroxidase is an enzyme found in potatoes that catalyzes the breakdown of hydrogen peroxide, H2O2, into O2 gas and water. We examined the different pH environments that can affect the enzyme activity during the breakdown of H2O2. In order to do this, we added different levels of pH, low, medium, and high, into different test tubes with the enzyme and H2O2, and we then inverted the tube. The amount of O2 gas produced was then measured and recorded.

The result was that the higher pH produced more gas, followed by medium pH, then low pH. The enzymes were more active in the pH of about 10. It increased the enzyme activity allowing more O2 to be produced from the breakdown of the hydrogen peroxide. INTRODUCTION In this lab we explore an enzymes activity and how it can be affected by changes to its environment. An enzyme is a protein and is a catalyst to chemical reactions (Raven, 2011). It helps accelerate reactions by lowering the activation energy, which is needed for reactions in cells to progress at a higher rate (Kaiser, 2001).

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Activation energy is the minimum amount of energy needed for a chemical reaction to occur, yielding products from a given set of reactants. Products are results of an enzyme cleaving to a specific substrate, by means of an induced fit. The induced fit is located at the active site of the enzyme or region of the enzyme where the substrate is bound. The substrate is the reactant within the reaction that fits with the enzyme like a key into a lock. Once the substrate enters the enzyme’s active site the enzyme can flexibly change shape to more snugly bind, via the induced fit,   to form an enzyme-substrate complex.

The substrate is then metabolized or broken down, resulting in a product, which can be utilized to energize cells. Once the product is released from the active site the enzyme returns to its original form (Raven, 2011). The main objective of this lab was to take the enzyme peroxidase and observe how well it acts as a catalyst to hydrogen peroxide in varying environments. The effectiveness of peroxidase was measured in a varying pH environment. The environment’s pH can range from   1-14, 7 being neutral, 7-1 being more and more acidic towards 1, and 8-14 being more and more basic towards 14 (Raven, 2011).

We hypothesized that a medium pH buffer added to the hydrogen peroxide an peroxidase reaction would be the best condition for the enzyme activity due to it being the more neutral than the high, being basic, and low, being acidic, pH. Level of Solution Each Time Interval | Low pHLevel of Gas in mL| Medium pHLevel of Gas in mL| High pHLevel of Gas in mL| Time Zero| 1. 5| 1. 5| 1. 6| 5 Minutes| 2. 7| 2. 5| 3. 5| 10 Minutes| 3. 1| 3. 4| 4. 5| 15 Minutes| 3. 5| 4| 5. 8| 20 Minutes| 4| 4. 5| 7| 25 Minutes| 4. 5| 5| 7. 9|

Total Gas in mL| 3| 3. 5| 6. 3| Table 1: This table shows the position that the solution was at inside the graduated tube it was held in at each time interval it was measured. Amount of O2 Produced in Time Figure 1: Amount of O2 gas curves to the time at which it was measured according to low, medium, and high pH. Bibliography Raven, Peter H. , & Johnson, George. 2011. Biology, 9th ed. McGraw-Hill, New York. Kaiser, Gary E. 2001. Enzymes. http://student. ccbcmd. edu/~gkaiser/biotutorials/proteins/enzyme. html.


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