Streptavidin is a 60,000 dalton protein isolated from the bacterium Streptomyces avidinii. Electrophoretically pure streptavidin was labeled with Cy3 using a proprietary method. DyLight conjugates provide increased brightness and greater protostability than other fluorophores (ex. - FITC). The conjugate is designed for use in immunofluorescence assays including flow cytometry, immunohistology, western blotting, microarrays and FLISA.