The Monolith NT™ Protein Labeling Kit provides convenient means for labeling small amounts (2 – 20 μM) of purified protein with our NT-547-MALEIMIDE 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-547-MALEIMIDE reactive dye contains Maleimide chemistry, which reacts efficiently with sulfhydryl groups of proteins to form highly stable dye-protein-conjugates. Sulfhydryl groups are found on cysteine residues which are usually solvent accessible and therefore suitable for labeling reactions. NT-547-MALEIMIDE dye labeled proteins show fluorescence excitation and emission maxima of approximately 557 nm and 574 nm, respectively.