| Avidin (Biotin Binding Protein) is a strongly basic glycoprotein synthesized in the hen oviduct and deposited in the albumen fraction of eggs at a ratio of 0.05% of the total protein content. It binds the water-soluble vitamin H (d-biotin) very tightly and specifically with a binding log constant of 15. Avidin is a tetrameric protein, composed of subunits of identical amino acid composition and sequence. Each monomer is glycosylated on Asn-17. The high affinity constant of Avidin for Biotin has been widely used in molecular biology: affinity chromatography, molecular recognition and labelling, Enzyme Linked ImmunoSorbent Assay (ELISA), histochemistry and cytochemistry. An excellent review in the field has been written by Wilchek, M. and Bayer, E.A., eds. (1990), Avidin-Biotin Technology, Methods in Enzymology, Vol.184, Academic Press. Molecular Weight: Monomer at 16.5kD. Dimer at 33kD and Tetramer at 66kD may also appear under incomplete denaturation. Source: Egg white Purity: Purified by chromatography. Protein: 0.90 mg protein/mg solid Protein Purity (10mg): Homogeneous by SDS Form: Supplied as a lyophilized powder. Activity: 12u/mg Unit Definition: One unit will bind 1ug of d-biotin at pH 8.9. Water: 5% Storage and Stability: Lyophilized powder may be stored at 4C. Stable for 6 months after receipt at 4C. Reconstitute with sterile buffer or ddH2O. Aliquot and store at 4C. Reconstituted product is stable for 6 months at 4C. For maximum recovery of product, centrifuge the original vial prior to removing the cap. |
