Ovomucoid

The ovomucoid is a highly glycosylated protein (it contains about 25% carbohydrates), made up of 186 amino acids, for a total weight of 28,000 Daltons. Typical of chicken egg white, it constitutes eleven percent of its protein fraction ; consequently, a medium-sized egg contains about 420 mg.

The ovomucoid molecule is composed of 3 domains, each of which - with antitrypsin activity - contains three disulfide bridges and two tyrosine residues.

The ovomucoid is known for two important characteristics:

1) antitrpsin activity;

2) allergenic properties in predisposed individuals.

1) Through its antitrypsin action, the ovomucoid hinders protein digestion within the intestine by inhibiting the proteolytic enzyme trypsin, produced by the pancreas in the form of an inactive precursor called trypsinogen.

The anti-proteolytic activity of the ovomucoid is partially inhibited by gastric pepsin, but it is still important to consume well-cooked egg whites to increase digestibility, inactivate avidin and reduce the risk of contracting food diseases such as salmonella.

2) The allergenic properties of the ovomucoid are linked to the "interaction of class E immunoglobulins (IgE-mediated allergic reactions) with specific structural components of the molecule (epitopes), and are largely responsible for allergic phenomena towards white d" egg.