Streptavidin
| Streptavidin ( Streptomyces avidinii ) | ||
|---|---|---|
|
||
| Monomeric subunit of streptavidin in the ribbon model with bound biotin ( calottes ) according to PDB 1STP | ||
| Mass / length primary structure | 159 amino acids | |
| Secondary to quaternary structure | Homotetramer | |
| Identifier | ||
| External IDs |
|
|
Streptavidin is a protein produced by bacteria of the species Streptomyces avidinii . The protein, made up of four identical protein subunits , has a molecular mass of around 60,000 Daltons ; each of the four subunits can bind one molecule of the vitamin biotin with a very high affinity (K a ~ 10 14 –10 15 M −1 ) . The streptavidin-biotin bond is one of the strongest known non-covalent biological bonds. In contrast to avidin (pre-calculated isoelectric point of 9.47), which can also bind biotin, streptavidin has an isoelectric point of 6.03 and therefore closer to the neutral range. Because of its lower overall charge and because streptavidin is not a glycoprotein and therefore does not bind to carbohydrate receptors, unspecific bindings are less common in streptavidin systems than when using avidin.
structure
The primary structure of the monomer, i.e. each of the four identical subunits, consists of 159 amino acids and has a molecular mass of 16.807 Da.
application
The streptavidin / biotin interaction is used in a wide variety of methods in biochemistry , immunology and molecular biology :
- Affinity chromatography
- Immunohistochemistry
- Immunassays
- Gene probe , single base extension
- DNA chip technology
swell
- ↑ Entry on streptavidin. In: Römpp Online . Georg Thieme Verlag, accessed on May 5, 2011.
- ↑ Louis Chaiet, Frank J. Wolf: The properties of streptavidin, a biotin-binding protein produced by Streptomycetes . In: Archives of Biochemistry and Biophysics . tape 106 , 1964, ISSN 0003-9861 , pp. 1-5 , doi : 10.1016 / 0003-9861 (64) 90150-x .
- ↑ ExPASy - Compute pI / Mw tool. In: web.expasy.org. Retrieved May 28, 2016 .
- ↑ UniProt P22629