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

Applications:
• 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