IA on effect of different pH on enzyme catalase (potato extract) on the rate of decomposition of H2O2 measured using a pressure sensor.

1. Centrifuge to spin down the extract Catalase extract (clear solution used) Potato, pressure sensor, H2O2
Diff pH buffer (1,4,5,7,9) were used.
To investigate the optimum pH for catalase activity
5% (v/v) H2O2 used.
Pressure sensor to measure O2 released.
Reaction mechanism
Procedure:
5g of potato added to 50ml water (10%) – centrifuge to collect extract
250ul catalase extract added to 1 ml of buffer of diff pH.
1 ml of mixture, added to 5ml of 5% H2O2
Rate was measured – change of pressure over time.
Hydrogen peroxide decomposition – O2 production
2H2O2→ 2H2O + O2
Effect of diff pH on enzyme catalase (potato extract) on the rate of decomposition of H2O2 measured using a pressure sensor.

2. Negative control - only pH without enzyme catalase
Positive control – only potato catalase without any pH buffer.
Pressure increase - due to enzyme catalase, and not pH.
pH Rate/kPas-1
1 0.01167
4 0.004171
5 0.01623
7 0.2128
9 0.1724
-ve control No change
Seems like amylase from potato extract function well in neutral/alkaline medium
Diff pH (1, 4, 5, 7, 9) were used
Effect of diff pH on enzyme catalase (potato extract) on the rate of decomposition of H2O2 measured using a pressure sensor.
0
0.05
0.1
0.15
0.2
0.25
1 4 5 7 9
Rate
of
decomposition
pH
pH vs rate of decomposition

3. Method 1 Method 2
Time Time
Volume Pressure
• Rate = Δ vol O2 over time
• Volume recorded
• Rate = Δ pressure O2 over time
• Pressure recorded
Procedure
2H2O2 → O2 + 2H2O
Rxn: H2O2 with diff (catalyst) measured using TWO diff methods
• 2H2O2 → O2 + 2H2O
(H2O2 limiting, KI excess)
• Pipette 1ml 1.0M KI to 20ml of 1.5% H2O2
• Vol O2 released recorded at 1 min interval
• Repeated using 3% H2O2 conc
Time/m Vol O2
(H2O2 1.5%)
Vol O2
(H2O2 3.0%)
0 0.0 0.0
1 8.5 14.0
2 15.0 26.5
3 21.0 34.0
4 26.0 39.0
Volume O2
Time
3 %
1.5 %
Effect of diff pH on enzyme catalase (potato extract) on the rate of decomposition of H2O2 measured using a pressure sensor.

4. • 2H2O2 → O2 + 2H2O
(H2O2 limiting, KI excess)
• Pipette 1ml 1.0M KI to 20ml of 1.5% H2O2
• Pressure O2 released recorded at 1 min interval
• Repeat using 3% H2O2 conc
Method 1 Method 2
Time Time
Volume Pressure
• Rate = Δ vol O2 over time
• Volume recorded
• Rate = Δ pressure O2 over time
• Pressure recorded
Procedure
2H2O2 → O2 + 2H2O
Time
3 %
1.5 %
Time/m Pressure O2
(H2O2 1.5%)
Pressure O2
(H2O2 3%)
0 101.3 101.3
1 102.4 103.4
2 103.5 105.6
3 110.3 115.2
4 113.5 118.2
Pressure O2
Rxn: H2O2 with diff (catalyst) measured using TWO diff methods
Effect of diff pH on enzyme catalase (potato extract) on the rate of decomposition of H2O2 measured using a pressure sensor.