Test for Enzyme Activity: Lab Report

Abstract

The purpose of this laboratory experiment was to investigate enzyme activity, enzyme specificity, and the effect of temperature on enzyme activity. The experiment involved testing the activity of catalase, an enzyme found in potatoes, by measuring the height of bubbles produced when it reacted with hydrogen peroxide under various conditions. The results indicated that temperature significantly influenced enzyme activity, with boiling water producing the highest level of activity. This finding contradicted the hypothesis that room temperature would yield the highest enzyme activity.

Introduction

Enzymes are biological catalysts that play a crucial role in facilitating biochemical reactions in living organisms. They enhance the rate of these reactions by lowering the activation energy required for the reaction to occur. Enzymes are highly specific, meaning that each enzyme typically catalyzes a specific reaction. Moreover, enzyme activity is influenced by various factors, including temperature.

The primary enzyme investigated in this experiment is catalase, which is found in potatoes. Catalase catalyzes the decomposition of hydrogen peroxide (H₂O₂) into water (H₂O) and oxygen (O₂). The overall reaction is represented as follows:

2 H₂O₂ → 2 H₂O + O₂

The rate of enzyme activity can be measured by observing the production of oxygen bubbles during this reaction. In this experiment, we aimed to investigate enzyme activity by measuring bubble height, test enzyme specificity using different solutions, and examine the effect of temperature on enzyme activity.

Hypothesis

It was hypothesized that room temperature conditions would yield the highest enzyme activity.

Materials

• 3% hydrogen peroxide
• Household blender
• 3 medium-sized potatoes (peeled and quartered)
• Tap water
• 8 test tubes
• 8 transfer pipets
• Sugar packets
• Salt
• Small saucepan
• Refrigerator with a freezer
• Stove
• 4 clear plastic cups
• Tongs (for handling test tubes)
• 4 coffee cups
• Cheesecloth (for filtering potato extract)
• Wax pencil or Sharpie marker
• Ruler
• Scale or balance
• 250 ml graduated cylinder
• Oven mitt or tongs (for handling hot objects)

Methods

Experiment 1: Testing for Enzymatic Activity

Step 1: Add 3 ml of the following solutions to labeled test tubes using fresh transfer pipets for each new solution:

• Test tube 1: Tap water
• Test tube 2: 1% sucrose solution
• Test tube 3: 1% salt solution
• Test tube 4: 3% hydrogen peroxide

Step 2: Add 2 ml of the catalase solution (liquid portion of the potato extract) to each test tube and place them in plastic cups to keep them upright.

Tap the bottom of each test tube to mix the contents and record the bubble height (if any) produced.

Experiment 2: Testing the Effect of Temperature on Enzyme Activity

Step 1: Label four test tubes as follows: test tube 1 (room temperature), test tube 2 (refrigerator), test tube 3 (freezer), and test tube 4 (boiling water). These represent the different temperature conditions for the experiment.

Step 2: Place a saucepan with tap water on a burner and bring it to a boil.

Step 3: Use a thermometer to identify and record the temperatures for room temperature, refrigerator, freezer, and boiling water. Record these temperatures in Table 2.

Step 4: Place the test tubes into separate coffee cups to maintain an upright position. Add 2 ml of the catalase solution to each test tube. Place test tubes 1, 2, and 3 in their respective temperature conditions. For test tube 4, fill a coffee mug halfway with boiling water and place test tube 4 in this container. Do not immerse the test tube in the boiling water.

Step 5: Allow the test tubes to sit for 5 minutes, then remove them from their respective conditions (use an oven mitt or tongs for the test tube exposed to boiling water).

Step 6: Add 3 ml of 3% hydrogen peroxide to all test tubes, swirl them, and measure the height of bubbles produced. Record this data in Table 2.

Results

Enzymatic Activity Test

Temperature on Enzyme Activity

Discussion

The results of the experiment demonstrated the influence of temperature on enzyme activity. In the first part of the experiment, where enzyme activity was tested using different solutions, it was observed that hydrogen peroxide produced the highest level of enzyme activity, as indicated by the significant bubble formation (2 cm). Conversely, the other solutions, such as tap water, 1% sucrose solution, and 1% salt solution, displayed lower enzyme activity, with shorter bubble heights (1 cm, 0.5 cm, and 0.1 cm, respectively).

These results suggest that catalase, the enzyme present in the potato extract, is highly specific to hydrogen peroxide and less effective in catalyzing reactions with other solutions. This supports the concept of enzyme specificity, where enzymes exhibit selectivity for particular substrates.

In the second part of the experiment, the effect of temperature on enzyme activity was investigated. Four different temperature conditions were tested: room temperature, refrigerator temperature, freezer temperature, and boiling water. The results showed a clear correlation between temperature and enzyme activity. Boiling water, with the highest temperature (215°F), produced the most significant enzyme activity, with a bubble height of 2 cm. Room temperature (76°F) resulted in moderate enzyme activity (0.5 cm), while refrigerator temperature (50°F) and freezer temperature (25°F) exhibited lower enzyme activity (0.3 cm and 0.1 cm, respectively).

These findings suggest that temperature has a substantial impact on enzyme activity. As temperature increases, the kinetic energy of molecules also increases, leading to more collisions between enzyme and substrate molecules. This, in turn, enhances the rate of enzymatic reactions. However, extremely high temperatures can denature enzymes, rendering them inactive.

Contrary to the initial hypothesis, which suggested that room temperature would yield the highest enzyme activity, the results indicated that boiling water produced the highest activity. This demonstrates the importance of considering the optimal temperature range for specific enzymes when designing experiments and predicting outcomes.

Conclusion

This laboratory experiment successfully investigated enzyme activity, enzyme specificity, and the effect of temperature on enzyme activity using catalase extracted from potatoes. The results highlighted the significant impact of temperature on enzyme activity, with boiling water producing the highest enzyme activity. The experiment also emphasized the concept of enzyme specificity, as catalase exhibited the most significant activity when reacting with hydrogen peroxide, its specific substrate. These findings contribute to our understanding of enzymatic reactions and the factors that influence them.

Recommendations

Based on the results of this experiment, the following recommendations can be made:

1. When conducting experiments involving enzyme activity, carefully consider the temperature conditions to optimize enzymatic reactions.
2. Ensure the use of fresh transfer pipets for each new solution to prevent contamination and obtain reliable results.
3. Explore further research on enzyme kinetics and the factors affecting enzyme activity to gain a deeper understanding of enzymatic reactions.