Pepsin Digestion of Protein

Students investigate the effect of pepsin on albumin, a protein, under different conditions. By comparing test tubes with acid, boiled enzyme, and water, they observe how pepsin activity depends on temperature and pH, simulating the digestive process in the stomach.

1. Label six test tubes: 1, 2, 3, 4, “Boiled,” and “Water.”
2. Add 5 mL of albumin suspension to tubes 1–4.
3. Add 5 mL of distilled water to the “Water” tube.
4. Add 2 mL of pepsin solution to the “Boiled” tube and heat until boiling, then cool.
5. Add 3 drops of dilute hydrochloric acid to tubes 2, 3, and 4; add 3 drops of distilled water to tube 1.
6. Warm all tubes in a 40°C water bath, including the boiled pepsin.
7. Add 1 mL of warm water to tube 2, 1 mL of boiled pepsin to tube 4, and 1 mL of warm pepsin to tubes 1 and 3.
8. Incubate for 6 minutes, then remove tubes and observe changes in cloudiness.
9. Record and compare results.

Proteolytic Enzymes | How Protein is Digested By Pepsin | Proteolytic Enzyme | ENGLISH - Solution- Pharmacy:

📄 BIO LAB: Enzyme Eggsploration - Southern Biological: https://www.southernbiological.com/content/BIO_P_BIOC_Y11%2612_1.pdf?srsltid=AfmBOoq6ZxpNR3f7B-kxrIHtypuXJwgnL7BtQSil0QPq_vdVYSXVBNpl

• Test different enzymes (e.g., trypsin) on the albumin suspension.
• Use different protein sources (milk casein, egg white) for digestion comparison.
• Alter pH conditions (neutral, alkaline) to study enzyme activity across pH ranges.

• Wear lab coat, gloves, and safety glasses at all times.
• Handle hydrochloric acid with care; it is corrosive.
• Use caution with hot equipment (Bunsen burner, boiling solutions).
• Do not consume any of the materials used.
• Wash hands and sterilize work surfaces before and after the experiment.
• Dispose of enzyme and protein solutions according to laboratory waste guidelines.

• Why does albumin appear cloudy before digestion? (Albumin proteins are insoluble; digestion breaks them into soluble peptides and amino acids.)
• Why does the boiled pepsin fail to digest albumin? (Boiling denatures the enzyme, preventing it from functioning.)
• Why is hydrochloric acid included in some tubes? (It simulates stomach acidity and provides optimal pH for pepsin activity.)
• What does the comparison between tubes 1 and 3 show? (Pepsin can function without acid but is much more efficient in acidic conditions.)
• What does tube 2 show about the role of acid alone? (Acid without pepsin does not digest albumin, so both enzyme and pH are required.)