Avidin, Biotin, Streptavidin

Efficiently create detection reagents, study protein-protein interactions, and more with high-quality avidin, biotin, and streptavidin reagents from Rockland.

We offer a comprehensive selection of avidin, biotin, and streptavidin already conjugated to fluorochromes and enzymes, as well as individual reagents that can be conjugated in your own lab.



The Advantages of Biotin-Avidin and Biotin-Streptavidin

The following properties of the biotin-avidin and biotin-streptavidin binding systems make them ideally suited for a wide variety of applications, including Western blotting, ELISA, FLISA, IHC, immunofluorescence microscopy, flow cytometry, ChIP, and protein-protein interactions:

High affinity

Avidin and streptavidin bind tightly to biotin (Kd ~1015 M)

High specificity

Avidin and streptavidin are highly selective for biotin, ensuring low background binding

High sensitivity

Because every avidin and streptavidin can bind four biotin moieties, tetravalent binding can increase detection sensitivity

Low perturbation

The small size of biotin typically has no effect on biological activity such as enzymatic catalysis or antibody binding

High stability

Because avidin and streptavidin are highly stable, they are amenable to a wide range of chemical modifications



Avidin vs Streptavidin

Avidin is a tetrameric biotin-binding glycoprotein with a molecular weight of approximately 62.4 kDa. Streptavidin has identical biotin binding properties compared with avidin, but lacks the glycoprotein portion of the molecule and therefore shows less non-specific binding. Streptavidin is a slightly smaller molecule with a molecular weight of approximately 53.6 kDa. The sequence of avidin only shows 30% homology with streptavidin, and anti-avidin and anti-streptavidin antibodies are not immunologically cross reactive.



Maximizing Signal Enhancement with Avidin and Streptavidin

While the basic configuration of biotin and streptavidin results in signal amplification, the incorporation of free avidin or streptavidin (S in the figure below) with biotinylated label (B-L) drives the formation of a polymeric complex that can increase detection sensitivity in many immunoassays.