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). Streptavidin 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 that results 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 Dilutions:
Immunofluorescence:1:20-1:50
Immunohistochemistry: 1:20-1:50
Immunocytochemistry: 1:20-1:50
Dilutions to be made with PBS, 10% normal goat serum.
Optimal dilutions to be determined by the researcher.
Absorption:
552nm
Emission:
565nm
Storage and Stability:
May be stored at 4 degrees C. For long-term storage, aliquot and store at 4 degrees C. Do not freeze. Aliquots are stable for at least 6 months. For maximum recovery of product, centrifuge the original vial prior to removing the cap. Further dilutions can be made in assay buffer. CY3 conjugates are sensitive to light.