Thermo Scientific™

NHS-Fluorescein (5/6-carboxyfluorescein succinimidyl ester), mixed isomer

Catalog number:  46410

 Related applications:

Protein Labeling & Crosslinking

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NHS-Fluorescein is an amine-reactive derivative of fluorescein dye that has wide-ranging applications as a label for antibodies and other probes, for use in fluorescence microscopy, flow cytometry and immunofluorescence-based assays such as Western blotting and ELISA. The NHS-ester of fluorescein efficiently labels antibodies and other purified proteins at primary amines (lysine side chains)

Properties of NHS-Fluorescein:

• Alternative name: 5/6-FAM SE
• Chemical name: 5/6-carboxyfluorescein succinimidyl ester
• Molecular weight: 473.4
• Excitation source: 488 nm spectral line, argon-ion laser
• Excitation wavelength: 494 nm
• Emission wavelength: 518 nm
• Extinction coefficient: > 70,000 M-1cm-1
• CAS #: 117548-22-8
• Purity: > 90% by HPLC
• Solubility: Soluble in DMF or DMSO
• Reactive groups: NHS ester, reacts with primary amines at pH 7.0 to 9.0

NHS-fluorescein is activated with the N-hydroxy-succinimidyl-ester (NHS ester) functional group. Compared to FITC, the NHS-ester deriviative has greater specificity toward primary amines in the presence of other nucleophiles and results in a more stable linkage following labeling. Pierce Amine-reactive Fluorescein Dyes are mixtures of isomers with reactive groups attached at the 5- and 6-positions of the bottom ring. The properties of these isomers are indistinguishable in terms of excitation and emission spectra, and for protein applications there is no need to isolate a specific isomer.

• Label antibodies for use as immunofluorescent probes
• Label oligonucleotides for hybridization probes
• Detect proteins in gels and on Western blots

Related Products
FITC (5/6-fluorescein isothiocyanate), mixed isomer
Pierce™ NHS-Fluorescein Antibody Labeling Kit
Pierce™ FITC Antibody Labeling Kit
For Research Use Only. Not for use in diagnostic procedures.


Label or Dye: FITC (Fluorescein), Fluorescein (FITC)
Chemical Reactivity: Amine
Excitation⁄Emission (nm): 494⁄518
Product Line: Pierce™
Product Size: 100 mg
Solubility: DMF (Dimethylformamide)

Contents & storage

Store desiccated at -20°C, protect from moisture


Manuals & protocols