Experiment – 2
To study the action of the pepsin enzyme under optimum conditions
Introduction
Pepsin
is an enzyme that aids in the breakdown of proteins and is secreted in the stomach of most animals. It functions at a very low pH, which makes it ideal to
use for studying the effect of pH on enzyme activity. Commercial or natural
albumin can be used as the protein source; however hardboiled egg white is more
impressive to demonstrate the action of pepsin.
1.
Egg
white (hard-boiled)
2.
Test
tubes (6)
3.
Test
tube rack
4.
Metric
ruler
5.
Knife
Solutions:
1.
1.0%
Pepsin
2.
0.4%
Hydrochloric acid
3.
Pepsin
(1.0%) in 0.4% hydrochloric acid
4.
0.5%
Sodium bicarbonate
5.
Pepsin
(1.0%) in 0.5% sodium bicarbonate
6.
Distilled
water
2. Fill each tube 1/3 full (5 ml) with the corresponding solution.
3. Drop a small (2 mm) cube of egg white into each tube.
4.
Incubate at room temperature for approximately 12 hours. (The speed of this
reaction can be increased by using very thin strips of egg white and/or
incubating at 30°C. Students might want to compare the action of papain under
similar conditions.)
5.
Examine tubes for the presence of the egg white.
After
12 hours, the egg white will be “digested” in tube B; little, if any, of the
cube will remain, while there appears to be little change in the other tubes.
If allowed to incubate longer, the cube in tube D and possibly C will decrease
in size.
Dr. Vidhin Kamble
Department of Zoology
Sangola College, Sangola
