PerCP-Cy5.5 is a popular tandem color used in flow cytometry. Its primary absorption peak is at ~480 nm with emission peak at ~700 nm. AAT Bioquest offers this preactivated PerCP-Cy5.5 to facilitate the PerCP-Cy5.5 tandem conjugations to reduced antibodies and other biomolecules that contain a thiol group. Our preactivated PerCP-Cy5.5 maleimide is prepared from the commonly used crosslinker SMCC, and ready to conjugate. PerCP (Peridinin-chlorophyll-protein complex) is isolated from Dinophyceae sp. Its tandem conjugates (such as PerCP-Cy5.5) can be excited with a standard 488 nm laser and emits in the far red at a longer wavelength for multicolor flow cytometric analysis of cells. These multiple emission wavelengths make PerCP- Cyanine conjugates potentially useful fluorochromes for multicolor analysis with FITC, PE and other fluorochromes. PerCP tandem structure may make it more photostable than PerCP alone, which generally photobleaches rapidly with more powerful water-cooled gas lasers.