Avidin
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- | + | <StructureSection load='2avi' size='350' side='right' scene='41/410356/Cv/4' caption='The avidin tetramer complex with biotin (PDB code [[2avi]])'> | |
- | + | __TOC__ | |
- | + | ==Function== | |
- | [[Avidin]] '''(Av)''' is a protein found in egg white which binds biotin (vitamin B7) with high affinity. This property makes it a powerful tool in various protein pull-down assays. Similar proteins are | + | [[Avidin]] '''(Av)''' is a protein found in egg white which binds biotin (vitamin B7) with high affinity. This property makes it a powerful tool in various protein pull-down assays. Similar proteins are:<br /> |
+ | * '''Streptavidin''' (StrAv) from the bacterium ''Streptomyces avidinii''<br /> | ||
+ | * '''Rhizavidin''' (RhiAv) from ''Rhizobium etli''<br /> | ||
+ | * '''Xenavidin''' from frog<br /> | ||
+ | * '''Zebavidin''' from zebrafish<br /> | ||
+ | * '''Tamavidin''' from fungi<br /> | ||
+ | * '''Bradavidin''' from ''Bradyrhizobium japonicum''<br /> | ||
+ | * '''Hoefavidin''' from ''Hoeflea phototrophica''<br /> | ||
+ | * '''Shwanavidin''' from ''Shewanella dentrifica''<br /> | ||
+ | * '''Wilavidin''' from ''Gammaproteobacteria bacterium'' forms biotin-binding hexameters<br /> | ||
+ | * '''AVR2''' and '''AVR4''' are avidin-related proteins. | ||
Avidin is one of the [[CBI Molecules]] being studied in the [http://www.umass.edu/cbi/ University of Massachusetts Amherst Chemistry-Biology Interface Program] at UMass Amherst and on display at the [http://www.molecularplayground.org/ Molecular Playground]. | Avidin is one of the [[CBI Molecules]] being studied in the [http://www.umass.edu/cbi/ University of Massachusetts Amherst Chemistry-Biology Interface Program] at UMass Amherst and on display at the [http://www.molecularplayground.org/ Molecular Playground]. | ||
+ | <scene name='41/410356/Cv/15'>Avidin is a tetrameric protein</scene> what in different words means that if we could, we would see a protein with four regions that look identical one to the other. However, to isolate the four regions as a whole in order to show the protein three dimensional structure has been quite diffucult so far and we just can see the three dimensional structure for <scene name='41/410356/Cv/16'>two of those four units</scene>. <ref group="xtra">PMID:8506353</ref><ref group="xtra">PMID:8344421</ref> | ||
- | + | {{Clear}} | |
+ | The binding affinity of biotin for the avidin <scene name='41/410356/Cv/17'>receptors</scene> is very hight or in other words, the strength of the interations between the biotin and the avidin receptors is so strong that washing the biotin-avidin complex is not enough to remove the ligand from its pocket. This is not even possible by adding more biotin molecules to the system avidin-biotin. Once a biotin has bound a pocket in the avidin, it is almost imposible to remove it in a biological system! | ||
- | + | Each monomer is an eight-stranded antiparallel <scene name='41/410356/Cv/18'>beta-barrel</scene>. Binding of biotin involves a highly stabilized network of polar and hydrophobic interactions. | |
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The presence of additional hydrophobic and hydrophilic groups in the binding site of avidin may account for its higher affinity constant. | The presence of additional hydrophobic and hydrophilic groups in the binding site of avidin may account for its higher affinity constant. | ||
- | Unexpectedly, a residual N-acetylglucosamine moiety was detected in the deglycosylated avidin monomer. These <scene name=' | + | Unexpectedly, a residual N-acetylglucosamine moiety was detected in the deglycosylated avidin monomer. These <scene name='41/410356/Cv/19'>sugars</scene> appear along with the biotin but outside of the biotin binding pockets. |
- | + | *<scene name='41/410356/Cv/20'>Biotin has bound a pocket in the avidin</scene>. | |
- | + | See also:<br /> | |
+ | * [[Molecular Playground/Streptavidin]] | ||
+ | * [[Streptavidin Binding Site]] | ||
+ | * [[Hila Cohen/Test Page]] | ||
+ | * [[Molecular Playground/Biotin binding avidin]] | ||
==About this Structure== | ==About this Structure== | ||
- | + | [[2avi]] is a 2 chains structure of sequences from [http://en.wikipedia.org/wiki/Gallus_gallus Gallus gallus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2AVI OCA]. | |
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== 3D structures of Avidin == | == 3D structures of Avidin == | ||
- | + | [[Avidin 3D structures]] | |
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- | + | </StructureSection> | |
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==Reference== | ==Reference== |
Current revision
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Reference
- Livnah O, Bayer EA, Wilchek M, Sussman JL. Three-dimensional structures of avidin and the avidin-biotin complex. Proc Natl Acad Sci U S A. 1993 Jun 1;90(11):5076-80. PMID:8506353
- Livnah O, Bayer EA, Wilchek M, Sussman JL. The structure of the complex between avidin and the dye, 2-(4'-hydroxyazobenzene) benzoic acid (HABA). FEBS Lett. 1993 Aug 9;328(1-2):165-8. PMID:8344421
Proteopedia Page Contributors and Editors (what is this?)
Michal Harel, Alexander Berchansky, Joel L. Sussman, Marcin Jozef Suskiewicz, Jaime Prilusky