Avidin is a so-called glycoprotein (complex of protein and carbohydrates), which is build from 128 amino acids and which is included in the egg white of bird and amphibian eggs. The proportion of carbohydrates in avidin is around 10%, the proportion of avidin in the total protein of egg white is about 0.05%.
Together with other components of the egg protein like e.g. lysozyme, ovomucoid and conalbumin, avidin seems to protect the egg white from microbial spoilage.
Avidin and biotin
With the vitamin biotin, avidin forms a complex that cannot be separated by protein-digesting (proteolytic) enzymes and therefore cannot be absorbed by the walls of the small intestine.
Therefore, regularly consumption of raw (chicken) eggs can lead to a biotin deficiency. By heating, avidin is (like every protein) denatured, so there is no danger of a biotin deficiency by eating boiled eggs.
Books on Amazon
- Avidin-Biotin Interactions: Methods and Applications in Molecular Biology
- Food Chemistry
- On Food and Cooking: The Science and Lore of the Kitchen
- Food Analysis (Food Science Texts Series)