5-TAMRA-streptavidin conjugate has been optimized in fluorophore/protein labeling ratio to ensure high fluorescent signal and uncompromised streptavidin function. 5-TAMRA is one of the most popular orange fluorophores used to label proteins. 5-TAMRA is the purified single isomer of 5-(and 6)-TAMRA that provides reproducibility for critical biological applications and avoids the inconsistency brought by minor positional difference between 5-TAMRA and 6-TAMRA. The fluorescence of 5-TAMRA can be observed at excitation/emission wavelength of 540 nm /575 nm. The 5-TAMRA-protein conjugates are very stable and suitable for immunofluorescent staining, fluorescence in situ hybridization, flow cytometry and other biological applications.