Description General description Avidin comprises of 0.05% of total egg white protein. It is a glycosylated protein. It corresponds to a molecular weight of 16.5 kDa and exists as tetramer, which can bind a minimum of three biotin molecules. Application Avidin is used for the purification of biotin containing proteins, which can enhance cellular binding and internalization of the antibody (Ab)-functionalized capsules compared with control human immunoglobulin (IgG)-functionalized capsules, suggesting these capsules can specifically interact with cancer cells through antibody/antigen recognition. Avidin-Agarose from egg white has been used: • in the precipitation of biotin tagged protein by pull down assay in neuroblastoma cell line (SH-SY5Y ) • in the purification of Lewis(x) sugar binding proteins from Schistosoma mansoni • in avidin bead assay for purification of labelled biotin • for capture of glycoproteins from murine cornea samples Biochem/physiol Actions Avidin finds biotechnological applications due to its high-affinity ligand binding property. Avidin interaction with biotin through its carbohydrate chains is widely exploited in biotechnological applications. In cancer cells, avidin-biotin systems helps in the in vivo localization and drug targeting in tumor cells. Unit Definition One unit will bind 1.0 μg of d-biotin. Physical form Suspension in 50% glycerol, 0.01 M sodium phosphate, pH 7.0, containing 0.02% sodium azide.