When you crack an egg into a pan, you can immediately see three parts. There is the yolk, a thin watery white, and a thick gelled white.
Egg white contains several mucoproteins, where the protein is attached to carbohydrates. In the egg, these serve as nutrients for the growing embryo, and as support and protection.
Over half of the protein in egg white is of one type – ovalbumin. It denatures at 176° Fahrenheit, forming the solid white mass we see at breakfast.