Streptavidin/FITC can be used in conjunction with biotinylated antibodies as an avidin/biotin labeling system for flow cytometry. Streptavidin (MW ~66kD) binds specifically with biotin (244D). It is derived from the bacterium Streptomyces avidinii and bears a remarkable similarity to chicken egg-white avidin both in three-dimensional structure and its ability to bind biotin with extremely high affinity (Kd=10e-15M). It is a tetrameric protein capable of binding up to 4 biotin molecules. Unlike avidin, Streptavidin is non-glycosylated and is essentially neutral in charge, whereas avidin (pH 10.5) is basic at neutral pH. Because of this, streptavidin has considerably less non-specific binding resulting in less background. It has replaced avidin as the reagent of choice for most applications where protein interactions may cause background. Application(s): Suitable for use in FLISA, Western Blot and Immunofluorescence. Other applications not tested. Recommended Dilution: Optimal dilutions to be determined by the researcher. Label: Fluorescein isothiocyanate (FITC) (Molecular Weight 390D) Absorption Wavelength: 495nm Emission Wavelength: 528nm Fluorochrome/Protein Ratio: ~3.7 moles FITC per mole of Streptavidin Storage and Stability: Lyophilized powder may be stored at 4C for short-term only. Reconstitute to nominal volume by adding sterile 40-50% glycerol and store at -20C. Reconstituted product is stable for 12 months at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.
Purity:
Purified by ion exchange chromatography. IEP Assay shows a single precipitin arc against source serum protein and IgG.
Form:
Supplied as a lyophilized powder in PBS, pH 7.2, 10mg/ml BSA, 0.09% sodium azide.
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