Avidin is a protein present in hen egg white and tissues of birds. In hens, it is synthesized in the oviduct and then deposited in the albumin where it protects chicken embryos from disease-causing organisms that require biotin (vitamin H) to grow.
With its remarkably high affinity for biotin, avidin tightly binds and sequesters biotin, depriving bacteria and other microbes of an essential growth factor.
The avidin-biotin binding system has been extensively applied in biotechnology and diagnostics. Avidin’s inherent characteristics have made this protein an effective natural compound used in the following fields:
- Biotin purification
- Chromosome visualization
Avidin’s rapid and almost irreversible binding to biotin supports many applications in both in vivo and in vitro research. Specific and tight binding to avidin can still occur when biotin has been bound to another compound through the use of a spacer arm. Cross linking with biotinylated molecules can occur under widely different experimental conditions and this has led to many innovative techniques in the fields of protein purification (affinity chromatography), affinity cytochemistry, and the study of cell surface molecular interactions.
There are virtually unlimited biochemical possibilities inherent in the avidin-biotin system, where affinity reactions are needed. A few examples of applications that have been developed for avidin include:
- Signal amplification in immunoassays.
- General diagnostics in the field of biology.
- Drug delivery, targeting and neutralization.
- Gene mapping.
The application of the avidin-biotin system requires the availability of various avidin-conjugated probes and many group specific derivatives, including enzymes, antigens, antibodies, lectins, hormones, nucleic acids, cells, and sub-cellular organelles. The ultra-high purity of Bioseutica’s avidin makes it particularly attractive for maximum efficacy of the various probes and derivatives, minimizing background interference.
- Avidin Activity
The avidin-biotin interaction is the strongest non covalent biological interaction (KD=10-15 M) between protein and a ligand. The bond formation between biotin and avidin is very rapid and, once formed, is unaffected by wide extremes of pH, temperature, organic solvents and other denaturing agents. The avidin-biotin complex is also resistant to enzymatic proteolysis.
Avidin is a remarkably stable protein and can withstand temperatures up to 70°C. It is highly soluble in water and salt solutions but under the appropriate conditions it can be crystallized using ammonium sulphate. Since tryptophan is involved in the binding site of avidin, it can be inactivated by oxidizing agents like ozone, periodate, H2O2 or intense light.
Avidin is a basic tetrameric glycoprotein with four identical subunits having a combined molecular weight of 64 kDa – 67 kDa. Avidin’s isoelectric point is approximately 10.5 and in monomeric form avidin contains 128 amino acid residues.
- Selling Unit: Grams (g)