Streptavidin is a non-glycosylated protein that is prepared chromatographically from the bacterium Streptomyces avidinii. Streptavidin homotetramers have a particularly high, non-covalent binding affinity for biotin. When conjugated with fluorochromes, streptavidin has been widely used with biotin-conjugated antibodies and other biotinylated specific-binding molecules (eg, recombinant proteins and lectins) to stain cells and tissues for subsequent multiparameter analysis by flow cytometry, fluorescence microscopy and imaging. Likewise, when conjugated with an enzyme (eg, Horseradish Peroxidase or Alkaline Phosphatase) and coupled with a colorimetric or luminescent substrate development system, streptavidin has found widespread use along with biotinylated antibodies in a number of applications including Western blot, ELISA, ELISPOT, immunocytochemistry and immunohistochemistry.
Streptavidin was conjugated to BD Horizon BUV563 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome of BD Horizon BUV395 which has an Ex Max of 348 nm and an acceptor dye. The tandem has an Em Max at 563 nm. BD Horizon BUV563 can be excited by the 355 nm ultraviolet laser. On instruments with a 561 nm Yellow-Green laser, the recommended bandpass filter is 585/15 nm with a 535 nm long pass to minimize laser light leakage. When BD Horizon BUV563 is used with an instrument that does not have a 561 nm laser, a 560/40 nm filter with a 535 nm long pass may be more optimal. Due to the excitation and emission characteristics of the acceptor dye, there may be spillover into the PE and PE-CF594 detectors. However, the spillover can be corrected through compensation as with any other dye combination.
