Streptavidin (FITC)

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. , Applications: , Suitable for use in Flow Cytometry and Immunohistochemistry. Other applications have not been tested. , , Recommended Dilution: , Flow Cytometry: 20ul of 1:10 dilution or 2ul of undiluted stock per 5x10e5 cells per test, Optimal dilutions to be determined by researcher. Cell Types Tested: Ficoll prepared human peripheral blood lymphocytes, CEM, HPB-MLT, Nalm-6, Jurkat, U- 937, Molt-4, Raji, Daudi and KG-1 (cells expressing Fc receptors were pre-blocked with human IgG), Storage and Stability: May be stored at 4°C. Do not freeze. Stable for at least 6 months at 4°C. 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. FITC conjugates are sensitive to light.