Product name:Avidin
CAS:1405-69-2
Specification:1mg
Description:
Avidin is a tetrameric biotin-binding protein produced in the oviducts of birds, reptiles and amphibians deposited in the whites of their eggs. In chicken egg white, avidin makes up approximately 0.05% of total protein (approximately 1.8 mg per egg). The tetrameric protein contains four identical subunits (homotetramer), each of which can bind to biotin (Vitamin B7, vitamin H) with a high degree of affinity and specificity. The dissociation constant of avidin is measured to be KD ≈ 10−15 M, making it one of the strongest known non-covalent bonds.
Avidin is a glycoprotein that can be extracted from egg whites. With a molecular weight of 60kD, each molecule is composed of 4 subunits, so it can be intimately bound to 4 biotin molecules. Plays an important role in immune mechanism.
Avidin, also known as ovalin or anti-biotin, has a molecular weight of 68000, pI 10 ~ 10.5. It is stable in pH9 ~ 13 buffer, resistant to heat and various proteolytic enzymes. Natural Avidin is a basic protein, consisting of 4 identical subunits to form a 4-polymer. Each Avidin subunit binds to the Ureido ring (I ring) of biotin via tryptophan residues in its structure. Therefore, there are 4 binding sites of one Avidin molecule to biotin molecule, and its binding constant (Ka) is as high as 1015mol/L.
In general, the active unit of Avidin is expressed by the amount of Avidin binding biotin, that is, the amount of Avidin needed to bind 1ug biotin is one Avidin active unit. Generally 1ug Avidin contains about 13 ~ 15 active units.