Avidin (AVD)

Avidin is a basic glycoprotein found predominantly in the egg white of birds such as chickens. Structurally, it consists of four identical subunits (homotetramer), each capable of binding one molecule of the vitamin biotin with extraordinarily high affinity (K_D ≈ 10^{-15} M). This makes the avidin-biotin interaction one of the strongest known non-covalent biological interactions. The natural function of avidin may be antimicrobial—by sequestering free biotin required by bacteria—but its primary importance lies in biotechnology. The unique binding properties are exploited widely for molecular detection systems including immunoassays (ELISA), Western blotting, immunohistochemistry, and various purification protocols using labeled or immobilized forms. While closely related structurally to streptavidin from bacteria—which lacks glycosylation—avidin’s carbohydrate content can lead to nonspecific interactions unless modified. Consumption risks arise only when large amounts are ingested raw due to interference with dietary biotin absorption; cooking denatures the protein and eliminates this effect[1][2][3][4].

Other names

AVDBiotin-binding protein

Not applicable for drugs targeting this molecule. In laboratory use: forms an extremely stable non-covalent complex with biotin or biotinylated compounds (K_D ≈ 10^{-15} M), enabling detection or purification of these molecules from complex mixtures[1][2][4].