Avidin from Egg White ~10-15 u/mg Protein, 100mg

Avidin is a basic glycoprotein consisting of four essentially identical subunits. The combined molecular weight of the subunits is about 66,000. Each subunit is a single polypeptide chain containing 128 amino acid residues with alanine at the N-terminal, glutamic acid at the C-terminal, and a carbohydrate moiety attached at the aspariginyl residue, position 17. It is isolated from raw egg white. It exhibits high binding affinity for biotin and is capable of producing biotin deficiency in rats and chicks. It also occurs in the white portion of eggs and the oviducts of birds and amphibia. It is destroyed by cooking or irradiation. Avidin was used in an assay using functionalized xenon as a biosensor to detect biotin-avidin binding. One unit will bind 1 µg of D-biotin at pH 8.9.