Avidin is a protein found in egg white that binds with biotin, found in egg yolk. In biochemical applications, streptavidin, which binds very tightly to biotin, is often used in place of avidin. A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Albumen redirects here. ... Biotin, also known as vitamin H or B7 and C10H16N2O3S (Biotin; Coenzyme R, Biopeiderm), is a water-soluble B-complex vitamin which is composed of an ureido ring fused with a tetrahydrothiophene ring. ... Biochemistry is the chemistry of life. ... Streptavidine (more commonly spelled streptavidin) is a tetrameric protein purified from Streptomyces avidinii that binds very tightly to the vitamin biotin with a dissociation constant (Kd) of ~ 10^(–15) M. This is one of the strongest biochemical interactions known, and is widely taken advantage of in scientific laboratories. ...

Relationship Between Avidin and Biotin

Avidin is a glycoprotein that has a very strong affinity for biotin with an Acid dissociation constant approximate to 1015 M^-1[1], the highest known between any ligand and a protein, and, as such, prevents biotins absorption in the gastrointestinal tract. Avidin is a tetrameric protein attaching four molecules of Biotin per tetramer. A glycoprotein is a macromolecule composed of a protein and a carbohydrate (a sugar). ... In chemistry and biochemistry, acid dissociation constant, the acidity constant, or the acid-ionization constant (Ka) is a specific type of equilibrium constant that indicates the extent of dissociation of hydrogen ions from an acid. ... It has been suggested that this article or section be merged with Ligand (biochemistry). ... Tetrameric flower of the primrose willowherb (Ludwigia octovalvis) showing four petals and four sepals In describing a flower, tetramery means that the flower parts are in fours: such as four petals in the crown. ...

Avidin-induced Biotin-deficient meals, especially those rich in egg white, make it impossible for biotin to be absorbed in the small intestine. Through the use of an enzyme, lyzine hydroxylase, and the intraveinous administration of avidinbiotin, complex biotin can be released into the system. Basically, Avidin is too large to absorb into the intestines, and by bonding tightly to Biotin, it makes the protein molecules of Biotin too large to pass into the intestine and get absorbed; And thus requires a complex procedure in order to be absorbed.

References

1. ^  Bayer, Ed: "The Avidin-Biotin Complex", Dept. of Biological Chemistry, Weizmann Institute of Science, Israel