Jackson Immuno Research Inc.
specializing in secondary antibodies and conjugates

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Fluorescent Dyes

Brilliant Violet™
421 & 480

  • Combine with AF488, RR-X, & AF647 for 5-color imaging
  • Compatible with commonly used filter sets
  • Switch nuclear stain from DAPI to DRAQ5™ for additional labeling options

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Fluorescein, FITC/DTAF

Fluorescein, FITC/DTAF Technical Information

FITC (Fluorescein isothyocyanate is the form of fluorescein used for conjugation to all of our antibodies and purified proteins, with the exception of streptavidin. Fluorescein conjugates absorb light maximally at 492 nm and fluoresce maximally at 520 nm. Although less bright than other green-fluorescing dyes, FITC is still a widely used fluorophore due to its long history. The major disadvantage of fluorescein is its rapid photobleaching (fading), which can be mitigated by the use of an anti-fading agent in the mounting medium. A better choice for many applications involving FITC is Alexa Fluor® 488 because it is brighter and more photostable.

FITC Spectra Excitation and emission spectra of FITC-conjugated affinity-purified secondary antibodies, streptavidin, and purified proteins. Peak heights have been normalized, spectra were obtained with an M-Series spectrophotometer system from Photon Technology International, Inc. Values are approximate, actual values may vary depending on the spectrofluorometer used in each laboratory.

DTAF (Dichlorotriazinylamino fluorescein) is another form of fluorescein, with excitation and emission peaks identical to those of FITC. We use DTAF (instead of FITC) only for conjugation with streptavidin, since fluorescence from FITC is greatly quenched after conjugation with streptavidin. This phenomenon is unique to streptavidin, and is not observed with antibodies.

Excitation Peak Emission Peak (nm)
Fluorescein, FITC/DTAF 493 519