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

Fluorescein dyes are used in wide-ranging applications including fluorescence microscopy, flow cytometry and immunofluorescence-based assays such as Western blotting and ELISA. FITC and NHS-fluorescein are reactive toward primary amine groups on proteins, peptides and other biomolecules, while fluorescein-5-maleimide and 5-IAF react with free sulfhydryls on cysteine residues.Most activated fluorescein derivatives are mixture 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. The single isomer is used in high resolution separation techniques such as sequencing and capillary electrophoresis.

Highlights:

• Amine-specific labeling: the NHS-ester or isothiocyanate efficiently labels antibodies and other purified proteins at primary amines (lysine side chains) Optimized 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 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