Steptavidin, a bacterial protein isolated from Streptomyces avidinii, is similar to egg-white avidin in its ability to bind biotin, and has been used as a replacement for egg-white avidin because of its more favorable chemical properties.
Conjugates of streptavidin are recommended for use with Biotin-SP-conjugated antibodies and Biotin-SP-conjugated ChromPure proteins.
Conjugate: DyLight™ 405
DyLight 405-conjugated secondary antibodies are excited maximally at about 400 nm and fluoresce with a peak at about 421 nm. They are very bright and photostable, but their optimal use is limited to microscopes or flow cytometers equipped with a 405 nm laser and a 420 nm emission filter. Under these conditions, it is possible to perform effective 4-color imaging with good color separation, good photostability, and high sensitivity. The combination of DyLight 405, Alexa Fluor® 488, Rhodamine Red-X, and Alexa Fluor® 647 provides for maximum color separation. Another 4-color dye combination, which may be equally effective but has slightly less color separation, is DyLight 405, Alexa Fluor® 488, Cy3, and Alexa Fluor® 647. DyLight 405 conjugates are the best choice for blue-fluorescing secondary antibodies in multi-color labeling protocols.