ARTS1630 Lecture 6: ARTS1630 WEEK 6

EXERCISE 4: Denaturation of Protein change in the structure of a protein that disrupts its function is known as denaturation. Heat, acid, base, alcohol and heavy metals may all cause denaturation. We will examine the effect of some denaturing agents on albumin, a protein found in egg whites. You will need: 3 egg whites Rubbing alcohol Vinegar A small pot with boiling water A wire whip or mixer Tablespoon Small container Crack open 4 eggs. Carefuly, separate the egg yolk from the egg white. For this exercise, you need the egg whites only 1. 2. Add 15 mL (one tablespoon) of egg white to a small container 3. Add 7.5 mL (1.5 teaspoons) of rubbing alcohol to the small container and gently mix. Wait 10 minutes. Record your observations here. 4. 5. Fill a small pot half-way with water. Bring the water to a boil. 6. Add 30 mL (two tablespoons) of egg white to the water 7. Wait several minutes until you see a change in the physical appearance of the egg white. 8. Record your observations here. 9. Add 15 mL of egg white to another small container. 10.Add 7.5 ml of vinegar to the small container and gently mix. 11. Wait 10 minutes. Record your observations here. 12. Take a wire whip or mixer and beat the remaining egg whites. Do this for several minutes (approximately 5 minutes) until you see a change in the physical appearance of the egg white. 13. Record your observations here 14. Why did the egg whites change appearance when mixed with alcohol, mixed with vinegar, added to boiling water, or agitated with the mixer? 15. Why is the physical appearance (structure) of protein so important? 16. Results of this experiment may vary depending on whether or not your egg whites were pasteurized. Pasteurization uses heat to destroy bacteria What effect could this have on your results?