The Biotin Streptavidin Interaction

Streptavidin and Biotin form the strongest noncovalent biological interaction

The affinity of streptavidin for biotin is the strongest noncovalent biological interaction known, with a dissociation constant (Kd) in the femtomolar range. Each streptavidin monomer can bind one biotin molecule, allowing a streptavidin protein to maximally bind four biotins.

Streptavidin Biotin interacts becoming biotinylated forming a Streptavidin - Biotin complex

The Streptavidin-Biotin Interaction

In addition to the strength of the interaction, the binding of streptavidin to biotin provides several further advantages:

  • Highly specific.
  • Rapid on-rate.
  • Resistant to changes in temperature or pH.
  • Can withstand the presence of organic solvents and denaturing agents.

Streptavidin and biotin are used extensively in a wide range of laboratory applications, and there are many ways in which their strong biological interaction can be exploited. Expedeon offers easy to use streptavidin and biotin products to streamline your research.

Streptavidin Conjugates

Streptavidin conjugates are extremely popular in techniques such as Western blottingELISA and Flow Cytometry. By attaching the streptavidin protein to a moiety such as a fluorophore, an enzyme or a gold nanoparticle, the streptavidin-biotin interaction can be employed as a detection method.

The use of a streptavidin conjugate as a detection reagent in an ELISA. In this example, the wells of a microplate have been coated with a specific capture antibody. The capture antibody has bound the target antigen in a sample, and a biotinylated antibody has then been added. The presence of antigen in the sample has been confirmed with a streptavidin conjugate. In an ELISA, the detection moiety would typically be a fluorophore or an enzyme.

Expedeon offers a range of streptavidin conjugates, manufactured using our Lightning-Link® and InnovaCoat® GOLD technologies. These conjugates are highly stable, since the streptavidin and the detection moiety are linked by a covalent bond. They are also fully scalable, allowing easy transfer from R&D to manufacturing.

Streptavidin fluorescent conjugatesStreptavidin enzyme conjugatesStreptavidin gold nanoparticle conjugates
Streptavidin-RPEStreptavidin-alkaline phosphatase20nm streptavidin-gold nanoparticle conjugate (10 OD)
Streptavidin-fluoresceinStreptavidin-HRP40nm streptavidin-gold nanoparticle conjugate (10 OD)

Streptavidin conjugates from Expedeon

Antibody labeling kits

Our Lightning-Link® conjugation kits allow direct labeling of antibodies, proteins, peptides, or any other biomolecule which contains free amine groups. The product range includes kits for labeling antibodies with streptavidin or biotin, as well as with enzymes or a wide range of fluorophores. The kits are incredibly quick and easy to use; the antibody is simply added to a vial containing the lyophilized label, incubated, and the conjugate is then ready. With no separation or washing steps required, 100% of the material is recovered.


The Lightning-Link® conjugation process.

Our Lightning-Link® kits have been widely published, with citations in over 300 journals to date. Why not take a look at our Lightning-Link® streptavidin and Lightning-Link® biotin references?

Biotinylated BSA

To complement our streptavidin products, we offer high-quality biotinylated BSA. This product is ideally suited as a plate coating reagent in an ELISA, and its use means that up to 10-fold less antibody is required for plate coating.

The streptavidin-biotin interaction

Biotinylated BSA for ELISA. The use of biotinylated BSA as a plate coating reagent significantly reduces the amount of antibody that is required, providing a significant cost saving.

For more information on any of our streptavidin or biotin products, please contact us.

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