HiLyte™ Fluor 555-streptavidin conjugate has been optimized in fluorophore/protein labeling ratio to ensure high fluorescent signal and uncompromised streptavidin function. The spectrum of HiLyte™ Fluor 555 is only slightly red-shifted compared to those of Cy®3 dyes, resulting in an optimal match to filters designed for Cy®3 dyes. The fluorescence of HiLyte™ Fluor 555 can be observed at excitation/emission wavelength of 554 nm /570 nm. HiLyte™ Fluor 555 is more photostable than Cy®3, providing researchers with additional time for capturing image. HiLyte™ Fluor 555 - protein conjugates can sustain treatments during immunofluorescent staining, fluorescence in situ hybridization, flow cytometry and other biological applications without hydrolysis.