The Monolith NT™ Protein Labeling Kit provides convenient means for labeling small amounts (2 – 20 μM) of purified protein with our NT-495-NHS fluorescent dye. This kit has been optimized for labeling proteins with molecular weights higher than 5 kDa, and contains everything needed to perform four labeling reactions and to separate the resulting conjugates from excess dye. Convenient gravity flow and spin columns are used to purify the labeled protein with high recovery yields (60 - 90 %) depending primarily on the molecular weight of the starting material. Labeling and purification can be completed in less than 60 minutes.

The NT-495-NHS reactive dye contains NHS-ester chemistry, which reacts efficiently with primary amines of proteins to form highly stable dye-protein-conjugates. Primary amine groups are found on lysine residues which are usually solvent accessible and therefore suitable for labeling reactions. NT-495-NHS dye labeled proteins show fluorescence excitation and emission maxima of approximately 493 nm and 521 nm, respectively.