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=10-e15M). 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 Immunofluorescence, Immunohistochemistry and Immunocytochemistry. Other applications not tested. Recommended Dilution: 1:20 to 1:50 dilution with PBS containing 10% normal goat serum. Optimal dilutions to be determined by the researcher. Storage and Stability: May be stored at 4C for short-term only. For long-term storage, store at -20C. Aliquots are stable for at least 6 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. CY5 conjugates are sensitive to light. Note: CY5 can be excited with a mercury lamp or with argon at 647nm.
Purity:
Purified
Form:
Supplied as a liquid in PBS, pH7.4, 1% BSA, 0.09% sodium azide. Labeled with CY5. Absorption: 650nm. Emission 667nm. Molar F/P ratio = 4
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