What is the role of pepsin and pancreatin in protein digestion? Where can these enzymes be found in the body?
Procedure:
A. Peptic digestion
1. Prepare 4 test tubes as follows:
Tube 1 - 3 ml pepsin
Tube 2 - 3 ml of 0.4% HCl
Tube 3 - 3 ml pepsin + 1.5 ml of 0.4% HCl
Tube 4 - 3 ml pepsin + 1.5 ml of 1% Na2CO3
2. Add equal slices of hard-boiled egg white to each tube.
3. Cover and incubate at 40oC for 2 hours.
4. Add 4 drops of toluene and store till the next lab period.
5. Determine the extent of digestion by visually noting the size of the hard-boiled
egg white in each tube.
6. Withdraw 1 ml of the supernatant liquid from each tube and place in 4
separate test tubes labelled tube 1a. 2a, 3a, 4a.
7. Neutralize tubes 2a& 3a with solid sodium carbonate.
8. To each supernatant liquid, add 1 ml of 10% NaOH and 2 drops of 1% CuSO4
.
Compare the colors obtained in the 4 tubes.
9. Place 1 ml of 0.5% peptone in a test tube and add 1 ml of 10% NaOH and 2
drops of 1% CuSO4
. Compare the result of these tubes with the other 4 tubes
above.
B. Pancreatin digestion
1. Prepare 4 test tubes as follows:
Tube 1 - 3 ml neutral pancreatin
Tube 2 - 3 ml water
Tube 3 - 3 ml water + 1.5 ml pancreatin
Tube 4 - 3 ml water + 1.5 ml pancreatin + 1.5 ml 1% Na2CO3
2. Place equal size of hard-boiled egg white in all tubes.
3. Place all tubes in water bath with a temperature maintained at 40oC for 1.5
hours.
4. Add 3 drops of toluene in all tubes and incubate till the next lab period.
5. Observe the size of the egg white in each of the tubes.
6. Take 1 ml of the supernatant in each tube and place in 4 separate test tubes
labelled 1b,2b,3b,4b. Add 1 ml of 10% NaOH and 2 drops of 1% CuSO4
in
each tube. Mix and compare the result of the 4 tubes.
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