Streptavidin is biotin-binding protein that was originally isolated from Streptomyces avidinii. In contrast to avidin, streptavidin has no carbohydrate and has a mildly acidic pI of 5. Thermo Scientific Pierce Streptavidin products use a recombinant form of streptavidin having a mass of 53,000 daltons and a near-neutral pI. Streptavidin is a tetrameric protein, with each subunit binding one molecule of biotin with affinity similar to that of avidin. Guanidinium chloride will dissociate avidin and streptavidin into subunits, but streptavidin is more resistant to dissociation.

Purified streptavidin and most of the conjugates are supplied lyophilized in phosphate-based buffers and may be reconstituted with water. Once reconstituted, these products are handled and stored similar to other proteins and enzyme conjugates (see the Tech Tip: Protein stability and storage). Alkaline Phosphatase conjugates are supplied as a liquid in a Tris-based buffer.

Applications for enzyme-labeled (HRP, AP) streptavidin

• Enzyme immunoassays (EIA)
• Cell and tissue staining (for light microscopy)
• Western blotting (WB) and other membrane-based biotin detection
• Also see our line of High Sensitivity Streptavidin Conjugates, which provide "poly-HRP" sensitivity and performance in many applications.

Applications for Fluorophore-labeled (FITC, TRITC, Texas Red) streptavidin

• Immunofluorescent assays (IFA)
• Tissue staining (for fluorescent microscopy)
• Blot immunostaining
• Cell staining (for fluorescent microscopy and activated cell sorting)
• Also see our complete line of DyLight Fluor Streptavidin Conjugates, which replace and surpass the performance of traditional fluorescein and rhodamine fluors in many fluorescence applications.

Related Products
High Sensitivity Streptavidin HRP Conjugates
High Stabilized (Pre-diluted) Streptavidin HRP Conjugates
DyLight Fluor Streptavidin Conjugates
Streptavidin Agarose Resin
NeutrAvidin Protein and Conjugates

Product #	Description	Pkg. Size
21122	Streptavidin	1 mg
21125	Streptavidin	5 mg
21135	Streptavidin	100 mg
21126	Streptavidin, Horseradish Peroxidase Conjugated Also consider our High Sensitivity Streptavidin-HRP Conjugates	1 mg
21124	Streptavidin, Horseradish Peroxidase Conjugated	2 mg
21127	Streptavidin, Horseradish Peroxidase Conjugated	5 mg
21324	Streptavidin, Alkaline Phosphatase Conjugated	1 mg
21323	Streptavidin, Alkaline Phosphatase Conjugated	3 mg
21224	Streptavidin, Fluorescein (FITC) Conjugated Also consider our complete line of DyLight Fluor Streptavidin Conjugates	1 mg
21724	Streptavidin, Rhodamine (TRITC) Conjugated	1 mg
21624	Streptavidin, Texas Red Conjugated	1 mg
21627	Streptavidin, R-Phycoerythrin Conjugated	1 ml
21629	Streptavidin, Allophycocyanin Conjugated	0.5 ml
21102	Maleimide Activated Streptavidin Protein for conjugation to sulfhydryl groups on antibodies and other molecules.	1 mg
21120	Streptavidin Hydrazide for conjugation to oxidized carbohydrates and aldehyde groups.	2 mg