This study intends to thoroughly investigate how inhibitors and changes in PH-value affect
catalase enzyme activity in the reaction as the enzyme catalase breaks down hydrogen
peroxide into water and oxygen, in the reaction 2 H2O2
(aq) → 2 H2O + O2
(g).
The task is: to analyze the results below discussing
- how a lead solution affects catalase enzyme activity, by referring to the results and
also to other sources. - how changes in PH-value affect catalase enzyme activity, by referring to the results
and also to other sources.
RESULTS:
Table 1 presents the observations and measurements from the experiment that examine the
effects of the inhibitor lead ion on the activity of the enzyme catalase. Test tube 9 containing
a solution of hydrogen peroxide with water only gave a relatively strong reaction with about
10.5 cm high foam. On the other hand, test tube 10 comprising a lead ion solution gave a
reaction which was rather weak with only 3 cm high foam amount.
Table 1 : Effect of the inhibitor lead ion on catalase enzyme activity
Variable Measurement Test tube 9 - deionized
H2O
Test tube 10 - with lead
ion solution
Amount of foam Cm high
from test tube
bottom
approx. 10.5 cm 3 cm
Reaction ef iciency
Description
relatively strong reaction relatively weak reaction
Data collected in Table 2 describe the investigation of how changes in the PH value affect
the enzyme catalase activity. The experiment was performed on three different PH values,
which are 6, 1.5 and 13 (see Table 2). At the pH value 6, which is closer to neutral, the
reaction shows a relatively strong efficiency with 10 cm high foam measured from the bottom
of the test tube. On the other hand, a very weak reaction resulted which is rather
imperceptible at both the low PH value 1.5 in test tube 7 and the high 13 in test tube 8. In
addition, no foams could be clearly observed, only small bubbles on the surface of the potato
pieces that resembled white lavar.
Table 2: Effect on catalase enzyme activity at different PH values
Variable Measurement Test tube 6 Test tube 7 Test tube 8
PH value PH 6 1.5 13
Reaction ef iciency
Description
relatively strong
reaction
very weak reaction
/ no reaction
Very weak reaction
/ no reaction
Amount of foam Cm high
from test tube
10 cm no foam could be
measured (small
no foam could be
measured (small
bottom bubbles) bubbles)
Method used is attached below in case it is needed.
METHOD USED:
Investigation of inhibitors effect:
Two test tubes with approximately 1 cm 3 of hydrogen peroxide solution (3% H 2 O 2) on
each were placed in a test tube holder. Later, 1 cm 3 of distilled water was added to one and
1 cm 3 of lead ion solution, i.e. lead nitrate Pb (NO3) 2 to the other. On each test tube,
another medium-sized piece of potato was added as a source of catalase. During the course
of the reactions, a number of observations regarding reaction efficiency were collected and
also the amount of foam formed was measured. The results of the different test tubes were
finally compared and presented in a table.
Investigation of PH effect:
Three test tubes were first placed in a test tube holder. To each of them was then added
about 1 cm 3 of hydrogen peroxide (3% H 2 O 2). The first was tested at a pH closer to
neutral at 6, the second at a low of 1.5 and the third at a high of 13. With a stir bar, the
hydrogen peroxide was mixed with 1 cm 3 of deionized water in the first test tube. To the
second test tube was then added 1 cm 3 of hydrogen chloride (hydrochloric acid, HCl) to
prepare an acidic solution. At the same time, a basic solution was formed by adding 1 cm 3
of sodium hydroxide (NaOH) to the third test tube. After the different PH values were
reached and checked using a PH meter, a medium-sized piece of potato was placed in each
of the test tubes. By testing the potato pieces at three different PH values, the effect of the
PH change was investigated, where both observations of reaction efficiency and
measurements of the amount of foam were completed after each reaction. Data collected
from this laboratory were then compared and analyzed in the form of a table.