Enzyme Catalysis Lab Report

Topics: Chemical reaction, Catalysis, Enzyme Pages: 5 (1002 words) Published: July 5, 2015
Candace S. Randolph
MISEP Cohort 2
Chemistry 512
Enzyme Catalysis Lab Report
Pre-lab Questions:
1. Write a balanced chemical equation with state symbols for the reaction catalyzed by peroxidase.
2H2O2  2H2O + O2
(4H1 4O)  (4H + 2O + 2O)
2. What is the substrate(s) of this reaction? What is the catalyst? Substrate = H2O2 hydrogen peroxide
Catalyst = peroxide
3. At what approximate temperature do enzymes normally operate in the body of a warm-blooded animal? Would your answer change if the enzyme came from a plant or yeast?
Enzymes normally operate in the body of a warm-blooded animal at the range of approximately 75°F - 100°F. If the enzyme came from a plant or yeast it would probably operate at a different temperature.

4. What allows peroxidase to be specific for its substrate? (In other words, why doesn’t peroxidase catalyze other types of reactions?)
Peroxidase is specific to its substrate because of its shape.

1

Experimental Lab:
Abstract:
An enzyme is a protein that serves as a biological catalyst (Denniston, 2007). A catalyst is any substance that increases the rate of a chemical reaction (by lowering the activation energy of the reaction) (Denniston, 2007). In this experiment we are using Hydrogen peroxide (the substrate for this experiment) is. Peroxidase is a soluble enzyme normally found in the cytoplasm of cells. Our experimental design was to find out if decreasing the amount of substrate will affect the reaction rate of the enzyme. For this experiment we used yeast as our peroxidase. The amount of enzyme was kept constant for this experiment. Because the catalyst remained constant the group’s original hypothesis was, as we decrease the amount of substrate reaction will speed up. (The slope of the line will get steeper.) We decreased the amount of substrate for each reaction assuming that the result would increase the reaction rate of the reaction. Materials:

Water
Yeast (enzyme)
Test tubes
Stoppers
Logger Pro and Laptop computer
Substrate (peroxidase)
Graduated cylinders
Eye droppers

2

Methods: (See lab directions...Jacobs for procedure notes)
Using a graduated cylinder (to measure accurately) pour the desired amount of substrate and water into each test tube. Do not mix the enzyme with the mixture until you are ready to measure the rate of reaction for each individual tube. In table 1 each tube is labeled with a letter and number. The 1’s are for the first trial and the 2’s are for the second trial. (If time permits, perform the experiment at least two times.)

1. Pour 5ml of substrate, 0ml of enzyme (no enzyme for negative control), and .5ml of water into test tube A1.
2. Seal test tube A1 with a stopper immediately after the enzyme is added. 3. Record the reaction rate using the Logger Pro software.
4. Repeat steps 1-3 using the new measurements as described in table 1. Table 1
Negative control
Positive control

Substrate
5ml (A1) (A2)
5ml (B1) (B2)
4ml (C1) (C2)
3ml (D1) (D2)
2ml (E1) (E2)
1ml (F1) (F2)

Enzyme
0ml
.5ml
.5ml
.5ml
.5ml
.5ml

Water
.5ml
0ml
1ml
2ml
3ml
4ml

Total
5.5ml
5.5ml
5.5ml
5.5ml
5.5ml
5.5ml

3

Results:
Trial #1

Reaction/Slope

Trial #2

Reaction/Slope

Average

A1
B1
C1
D1
E1
F1

No change
0.4076 kPa/s
0.3365 kPa/s
0.2825 kPa/s
0.1983 kPa/s
0.09574 kPa/s

A2
B2
C2
D2
E2
F2

No change
0.4309 kPa/s
0.3424 kPa/s
0.2649 kPa/s
0.2207 kPa/s
0.09713 kPa/s

No change
0.41925 kPa/s
0.33945 kPa/s
0.2737 kPa/s
0.2095 kPa/s
0.096435 kPa/s

Standard
Deviation
± .0132
± .00205
± .0062
± .0079
± 5.3577-5

The above table summarizes the result of the experiment. The experiment was performed two times. The average reaction (slope) is in column five and the standard deviation is noted in column six. Our original hypothesis was that as we decrease the amount of substrate reaction will speed up. (The slope of the line will get steeper.) We were incorrect. As we decreased...
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