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Activity
2: The Denaturation of Proteins
Have
you ever had to separate the yolk of an egg from the egg white
for a recipe? Egg white consists mostly of a protein called
albumin. In this experiment, you will test how denaturation
of a protein (albumin from egg white) affects the protein's
solubility (ability to dissolve) in water.
 1.
Carefully break an egg and pour out the white part into a dish,
leaving the yellow yolk part behind. Be careful not to break
the yolk. Do not get
any egg yolk in dish.
2.
Take a small fraction of the egg white and put it in a glass
of water. What happens? Does it dissolve?
 3.
Heat the egg white, which is mostly albumin protein, until it
cooks. How does the appearance change?
4. Cut a small piece of
the cooked egg white and put it in the same volume of water
that you used in step 2 above. Does it dissolve?
Interpretation:
Why does heating cause a change in appearance? Why does heated
egg white not dissolve? When you fry an egg, why does the white
congeal first before the yolk? All of these questions can be
answered by thinking about the hydrogen-bond basis for coiling
and folding of proteins.
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