Ovotransferrin

Ovotransferrin, also called conalbumin, is a major iron-binding glycoprotein of egg white. It is a member of the transferrin family and is the second most abundant protein in the white, after ovalbumin. In chickens, the protein is produced by oviductal secretory cells and secreted into the egg white during formation.

The mature protein is about 77-79 kDa and consists of two lobes, N and C, each capable of binding one ferric iron ion (Fe3+) in the presence of a carbonate synergist. Like other transferrins, ovotransferrin binds iron with high affinity at neutral pH and releases it under acidic conditions. It is also a glycoprotein, with N-linked carbohydrate chains that influence stability and protection against proteolysis.

In egg white, ovotransferrin contributes to innate defense by sequestering iron, an essential nutrient for many microbes, thereby inhibiting growth. Upon proteolytic digestion or under acidic conditions, it can release iron and generate peptide fragments with additional antimicrobial activity. Its abundance in egg white and its iron-chelating properties have inspired interest in food science and nutraceutical applications as a source of bioactive peptides.

Ovotransferrin is commonly referenced alongside other transferrins and iron-binding proteins. It is named conalbumin in some early literature, and the gene encoding it in birds is TF. Together with ovalbumin and other albumen components, ovotransferrin helps protect the developing embryo from microbial invasion while contributing to the nutritional profile of the egg.