Ovalbumin

Overview
Ovalbumin is the main protein found in egg white, making up 60-65% of the total protein. It belongs to the serpin superfamily of proteins, although unlike the majority of serpins it is unable to inhibit any proteases.

The function of ovalbumin is unknown, although it is presumed to be a storage protein.

Research
Ovalbumin is an important protein in several different areas of research, including:


 * general studies of protein structure and properties (because it is available in large quantities).


 * studies of serpin structure and function (the fact that ovalbumin does not inhibit proteases means that by comparing its structure with that of inhibitory serpins, the structural characteristics required for inhibition can be determined).


 * proteomics (chicken egg ovalbumin is commonly used as a molecular weight marker for calibrating electrophoresis gels).


 * immunology (commonly used to stimulate an allergic reaction in test subjects).

Structure
The ovalbumin protein of chickens is made up of 385 amino acids, and its relative molecular mass is 45 kD. It is a glycoprotein with 4 sites of glycosylation.

It is secreted from the cell, despite lacking an N-terminal leader sequence.

Medicinal characteristics
In cases where poisoning by heavy metals (such as Iron) is suspected, ovalbumin may be administered. Ovalbumin chelates to heavy metals and traps the metal ions within the sulfhydryl bonds of the protein. Chelating prevents the absorption of the metals into the gastrointestinal tract and prevents poisoning.