Thermo Scientific™

Pierce™ NHS-Fluorescein Antibody Labeling Kit

Catalog number:  53029

 Related applications:

Protein Labeling & Crosslinking

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The Thermo Scientific NHS-Fluorescein Antibody Labeling Kit is a multi-component kit containing a high-performance derivative of fluorescein dye, activated for easy and reliable labeling of antibodies, proteins and other molecules for use as fluorescent probes.

Features of the kit:

Easy —convenient kit with NHS-fluorescein to label and purify antibody in about one hour
Amine-specific labeling—the isothiocyanate variety of fluorescein efficiently labels antibodies and other purified proteins at primary amines (lysine side chains)
Optimized kit procedure—following the standard protocol results in antibodies with excellent dye:protein ratios for optimum activity and fluorescence
Single-use fluors—no need to weigh tiny amounts of powder; kits contain single-use vials of reagent
Efficient purification—kits include purification resin and easy-to-use spin columns, ensuring rapid and efficient removal of non-reacted dye and excellent protein recovery

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.

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

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

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


Excitation⁄Emission (nm): 494⁄518
Label or Dye: Fluorescein (FITC)
Labeling Scale: 0.5-1 mg
Labeling Target: Antibodies (General), Proteins (General)
Product Line: Pierce™
Product Size: 3 reactions

Contents & storage

Sufficient For: Labeling and purifying 3 x 1 mg (2 mg/mL) of IgG or other proteins
• NHS Fluorescein, 3 x 50 µg vials
• Borate Buffer, 1 mL
• Purification Resin, 5 mL
• Spin Columns, 6 each
• Collection Tubes, 12 each

Store NHS-Fluorescein at -20°C. Store other kit components at 4°C.


Manuals & protocols