Biotin-binding proteins

Avidin (from egg white) [1405-69-2] Mr -70,000. Purified by chromatography of an ammonium acetate soln on CM-cellulose [Green Biochem J 101 774 1966]. Also purified by affinity chromatography on 2-iminobiotin-6-aminohexyl-Sepharose 4B [Orr 7 Bio/C/iew 256 761 1981]. It is a biotin binding protein. 

The presence of biotin labels on an antibody molecule provides multiple sites for the binding of avidin or streptavidin. If the biotin binding protein is in turn labeled with an enzyme, fluoro-phore, etc., then a very sensitive detection system is created. The potential for more than one labeled (strept)avidin to become attached to each antibody through multiple biotinylation sites provides an increase in detectability over antibodies directly labeled with a detectable tag. 

Chaiet, L., and Wolf, F.J. (1964) The properties of streptavidin, a biotin-binding protein produced by Streptomycetes. Arch. Biochem. Biophys. 106, 1-5. 

Acetyl CoA carboxylase Fatty acid synthesis of raw eggs (contain avidin, a biotin-binding protein)... 

C. Biotin and the Formation of Carboxyl Groups from Bicarbonate 728 Box 14-B The Biotin-Binding Proteins Avidin and Streptavidin... 

Biotin 515, 516,711, 721, 723 - 730,723s biosynthesis of 718, 745 in enzymes, table 724 mechanism of action 725 - 729 nutritional requirement 756 Biotin-binding proteins 728 Biotin carboxylase 724 Biotin carboxyl carrier protein 724 Biotin holoenzyme synthetase 724... 

The relative bioavailability of free and bound biotin is not entirely clear (179,180) for example, the biotin present in many cereals and oilseeds is largely unavailable to animals. In addition, the bioavailability of biotin can be significantly impaired by avidin, a biotin-binding protein found in egg white. The physiology and metabolism of biotin has been recently reviewed (179,180). 

Streptavidin is another biotin binding protein isolated from Streptomyces avidinii that can overcome some of the nonspecificities of avidin (Chaiet and Wolf, 1964). Similar to avidin, streptavidin contains four subunits, each with a single biotin binding site. After some postsecretory modifications, the intact tetrameric protein has a molecular mass of about 60,000 D, slightly less than that of avidin (Bayer et al., 1986, 1989). 

Antibodies can be conjugated to biotin by a number of chemical means. They can then be used in immunochemical procedures in conjunction with secondary reagents coupled to biotin-binding protein proteins such as avidin. 

Hirsch, J. D., Eslamizar, L., Filanoski, B. J., Malekzadeh, N., Haugland, R. P., Beechem, J. M., and Haugland, R. P. (2002) Easily reversible desthiobiotin binding to streptavidin, avidin, and other biotin-binding proteins uses for protein labeling, detection and isolation. Anal. Biochem. 308, 343-357. 

Bayer EA, Wilchek M. Biotin-binding proteins Overview and prospects. Methods Enzymol 1990 184 49-51. 

Dakshinamurti K and Chauhan J (1994) Biotin-binding proteins. In Vitamin Receptors Vitamins as Ligands in Cell Communication, K Dakshinamurti (ed.), pp. 200 9. Cambridge, UK Cambridge University Press. 

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