The white albumen acts as a nutrient store, an immune barrier, an insulating gel buffer to absorb the shocks of being moved. Albumen holds a store of water inside the amniotic membranes that prevent dessication.

The albumen contains a number of protease inhibitors that prevent protein digestion by proteases and protect the albumen protein's structural integrity from microbial infection. Avidin binds biotin (vitamin B7) and is thought to have an antibacterial function that inhibits bacterial growth like streptavidin. Flavoprotein is a class with members that protect against oxidative stress. The combined functions of the proteins are nutritional and protective.

The most abundant nutrient in egg whites is protein. The white from one large egg contains 3.6 grams of protein, and roughly 85 percent of the egg white's calories come from its protein content. Like other animal sources of protein, egg whites provide all the essential amino acids your body needs from your diet. You use these amino acids to make new proteins within your cells and tissues, and also utilize some amino acids to support nervous system function. A single egg white contributes approximately 5 percent to your daily protein requirements if you follow a 2,000-calorie diet, according to the Harvard School of Public Health.

Purposes of some of the protein in egg white:

"

54% Ovalbumin - Nourishment

12% Ovotransferrin - Binds iron

11% Ovomucoid - Blocks digestive enzymes[citation needed]

4% Ovoglobulin G2

4% Ovoglobulin G3

3.5% Ovomucin

3.4% Lysozyme - Kills bacteria

1.5% Ovoinhibitor

1% Ovoglycoprotein

0.8% Flavoprotein

0.5% Ovomacroglobulin

0.05% Avidin

0.05% Cystatin"

http://en.wikipedia.org/wiki/Egg_white

this protein is for future embryo.It acts as a parental food.

food for the baby if the yolk is fertilized