Enzyme Lab
By: Gaurav Sahota
March 19, 2014
Ms. Lukas

Background Information: This lab discusses the enzyme, Catalase, and the factors that affect its performance. An enzyme is a biological catalyst that speeds up reactions. Catalase catalyzes the decomposition of hydrogen peroxide to water and oxygen. Catalase has an optimal pH level of 7.0. The concentration of both the enzyme and the substrate will influence the rate of a catalysis reaction. If there is excess substrate present, then the rate of reaction is proportional to the enzyme concentration. The rate of reaction increases as collisions become more frequent. However, as the enzyme molecules approach the maximum rate at which they combine with the substrate, increasing the substrate concentration has a reduced effect. Eventually, the rate of reaction levels off.

Purpose: To examine the factors that affects the performance of the enzyme Catalase.
Hypothesis:
Part A: It was thought that the amount of gas that was produced in the graduated cylinder would increase as the time increased for any amount of disks placed on the wall of the cylinder.
Part C: It was estimated that the amount of gas would increase as the pH level put into the cylinder grew.
Part D: It was thought that as the substrate concentration increased, the enzyme activity would also increase.
Equipment:
Table 1.1: Apparatus
Beet liver
Hydrogen peroxide
Test tubes
Trough
Plastic tubing
Graduated cylinder
Hot plate
Freezer
Small disks
Hydrochloric acid
Sodium hydroxide
Cell phone(timing device)

Method-
Part A:
Obtain a small amount of the beet liver milkshake (50 mL).
Dip one disk into the liver and ensure that the disk is saturated
Place 10 mL of 3% hydrogen peroxide in a test tube, stick the disk to the side of the test tube. Place the rubber stopper with the plastic tubing into the test tube
Fill the graduated cylinder with water and invert into the water trough so that none escapes
When the apparatus is set up invert the test tube so that the substrate and enzyme mix. Collect the gas produced in the graduated cylinder. Begin timing as soon as this happen.
Record the amount of gas collected every 10 seconds for 100 seconds.
Graph your results
Repeat steps 2-7 with 3 and 5 disks
Part C:
Repeat steps 2-7 of part A using 2 disks of enzyme at a pH of 5-6.
Repeat steps 2-7 of part A using 2 disks of enzyme at a pH of 2-3
Repeat steps 2-7 of part A using 2 disks of enzyme at a pH of 10-11

Part D:
Place 2 disks of enzyme on the side of a test tube containing 10 mL of peroxide. Mix the substrate and enzyme. Let reaction continue until completion
Remove the disks of enzyme and place on the side of a second test tube of a new peroxide
Place 2 new enzyme disks in the test tube of old peroxide.
Mix the contents of both tubes and observe
Observations:
Part A-
Table 1.2: Observations of Part A (changing enzyme concentration)

Amount of Gas (mL)
Time (s)
1 disk
3 disk
5 disk
10
10
20
23
20
14
26
31
30
18
30
39
40
25
35
46
50
28
40
54
60
32
44
64
70
36
49
70
80
39
53
77
90
43
58
85
100
47
64
92

Part C:
Table 1.3: Observations of Part C (changing pH levels)

Amount of Gas (mL)
Time (s) pH2 pH6 pH11 10
5
10
15
20
9
14
20
30
12
18
27
40
14
23
38
50
15
26
44
60
17
30
49
70
19
33
52
80
21
39
54
90
22
44
54
100
24
50
56

Part D-
Table 1.4: Observation of Part D (changing substrate concentration)

Amount of Gas (mL)
Time (s)
3% H2O2
2% H2O2
1% H2O2
10
29
19
7
20
38
20
12
30
48
21
14
40
68
24
20
50
80
31
30
60
88
35
36
70
88
39
43
80
88
44
47
90
88
50
50
100
88
54
50

Analysis:
1) Enzyme concentration is directly proportional to the enzyme activity. As enzyme concentration decreases, the enzyme activity also decreases. This happens because if there is less enzymes, the chance of a collision happening between an enzyme and a substrate is much lower. That causes the lower rate of reaction.
2) As substrate concentration increases, the enzyme activity also increases to a certain point at