Avidin
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Ongoing Trials on Avidin at Clinical Trials.gov Clinical Trials on Avidin at Google
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US National Guidelines Clearinghouse on Avidin
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Directions to Hospitals Treating Avidin Risk calculators and risk factors for Avidin
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Overview
Avidin is a glycoprotein found in the egg white and tissues of birds, reptiles and amphibians. It contains four identical subunits having a combined mass of 67,000-68,000 daltons. Each subunit consists of 128 amino acids and binds one molecule of biotin. The extent of glycosylation is very high. Carbohydrate accounts for about 10% of the total mass of avidin. Avidin has a basic isoelectric point (pI) of 10-10.5 and is stable over a wide range of pH and temperature. Extensive chemical modification has little effect on the activity of avidin, making it especially useful for protein purification. Because of its carbohydrate content and basic pI, avidin has relatively high nonspecific binding.
Relationship between avidin and biotin
Avidin has a very strong affinity for biotin with a KD (dissociation constant) of approximately 10-15 M-1, the highest known affinity between any protein and its ligand, and, as such, prevents biotin absorption in the gastrointestinal tract. In biochemical applications, streptavidin or NeutrAvidin, which also bind very tightly to Biotin, are often used in place of avidin.
Avidin's affinity for biotin is exploited in wide ranging biochemical assays, including western blot, ELISA, ELISPOT and pull-down assays. Avidin immobilized onto solid supports is also used as purification media to capture biotin-labelled protein or nucleic acid molecules. For example, cell surface proteins can be specifically labelled with membrane impermeable biotin reagent, then specifically captured using an avidin-based support.
References
- ^ Bayer, Ed: "The Avidin-Biotin Complex", Dept. of Biological Chemistry, Weizmann Institute of Science, Israel
External links
Proteins: albumin | |
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| Egg white (albumEn) | Conalbumin - Ovalbumin - Avidin |
| Serum albumin | Human serum albumin - Bovine serum albumin - Prealbumin |
| Other | C-reactive protein - Lactalbumin - Parvalbumin - Ricin |
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
