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AAT Bioquest - Biotin-Streptavidin Conjugation System
The widespread adoption of the biotin-streptavidin conjugation system is primarily due to two factors. The first is the relatively small size of the biotin and streptavidin molecules themselves, which allows for extensive binding to biologically active macromolecules, such as antibodies, without impedance to their functions (i.e. an antibody`s binding site). The second is the specificity with which biotin and streptavidin bind to each other, as well as the strength of the subsequent bond, which allows for powerful, stream-lined bioassay applications. Streptavidin tetramers have an extraordinarily high binding affinity for biotin with a dissociation constant (Kd) of approximately ~10-14 mol/L. This tight and specific binding is rapid and able to withstand extremes in pH, temperature, organic solvents, and denaturing reagents.
A key benefit of the biotin-streptavidin system is its ability to improve detection sensitivity. This in large part is due to the tetrameric conformation of streptavidin. One streptavidin protein has the capacity to bind four biotin molecules with high affinity and selectivity. This multiplicity enables the amplification of weak signals and improves the detection sensitivity for medium- and low-abundance targets in mammalian cells or tissues with a simple workflow.
Another key benefit is the versatility of the biotin-streptavidin system. Because streptavidin can be conjugated to a variety of reporter tags, it can be readily incorporated into virtually every immunoassay. For example, enzyme conjugates of streptavidin are widley used in enzyme-linked immunosorbent assays (ELISAs), while fluorescently labeled streptavidin, such as iFluor™ 488 streptavidin, are widely used in cell surface labeling, fluorescence activated cell sorting (FACS) and other fluorscence imaging applications.
- Enzyme-linked immunosorbent assay (ELISA)
- Immunohistochemistry (IHC)
- Power Styramide™ Signal Amplification, a superior replacement for tyramide
- Immunoblotting
- Immunofluorescence microscopy
- Cell surface labeling
- Affinity purification
- Fluorescence-activated cell sorting (FACS)
- Flow cytometry