• Fluorescently label up to 1 mg of protein per reaction (three reactions per kit)
• Label 0.5–3 mg per reaction with DSB-X Biotin Protein Labeling Kit (five reactions per kit)
• Labeled proteins ready to use in 90 min. (∼15 min. hands-on time)
• Rapidly purify proteins by quickly removing unbound dye using pre-packed Zeba Dye and Biotin Removal Spin Columns (7K MWCO, Cat. No. A44299) for >85% recovery
• Includes detailed instructions for determining degree of labeling (DOL)

Each protein labeling kit contains everything you need to perform 3-5 separate labeling reactions and purify the resulting conjugates. The reactive dye has either a succinimidyl ester (SE) or a tetrafluorophenyl (TFP) ester moiety that reacts efficiently with primary amines of proteins to form stable dye–protein conjugates. Each of the vials of reactive dye provided in the kit is sufficient for labeling 1 mg of a variety of purified proteins, including growth factors, cytokines, nanobodies, enzymes, cell-adhesion molecules, and antibodies.

Direct labeling with fluorophores allows multiple primary antibodies of the same isotype (derived from the same species) to be used in the same experiment. Stabilizing proteins such as BSA should be removed from the sample before labeling.

The different protein labeling kits

• Blue-fluorescent Alexa Fluor 350 —excitation and emission maxima of 346/442 nm
• Green-fluorescent Alexa Fluor 488 – excitation and emission maxima of 494/519 nm; excited using a 488 nm argon laser line and detected under standard FITC/Cy2 filters
• Yellow-fluorescent Alexa Fluor 532 – excitation and emission maxima of 530/554 nm; excited using a 532 nm Nd:YAG laser line and detected under standard Rhodamine 6G filters
• Orange-fluorescent Alexa Fluor 546 – excitation and emission maxima of 554/570 nm; excited using a 543 nm He-Ne laser line and detected under standard TRITC/Cy3 filters
• Orange-fluorescent Alexa Fluor 555 – excitation and emission maxima of 555/565 nm; excited using a 543 nm He-Ne laser line and detected under standard TRITC/Cy3 filters
• Orange-red-fluorescent Alexa Fluor 568 – excitation and emission maxima of 577/603 nm; excited using a 568 nm Kr laser line and detected under standard Rhodamine Red/Cy3.5 filters
• Red-fluorescent Alexa Fluor 594 – excitation and emission maxima of 590/617 nm; excited using a 594 nm Kr or He-Ne laser line and detected under standard Texas Red filters
• Far-red-fluorescent Alexa Fluor 633 – excitation and emission maxima of 632/647 nm
• Far-red-fluorescent Alexa Fluor 647 – excitation and emission maxima of 650/668 nm; excited using a 633 or 635 nm Kr or He-Ne laser line and detected under standard APC/Cy5 filters.
• Far-red-fluorescent Alexa Fluor 660 – excitation and emission maxima of 663/690 nm
• Near-IR-fluorescent Alexa Fluor 680 – excitation and emission maxima of 680/700 nm
• Green-fluorescent Fluorescein-EX – excitation and emission maxima of 494/518 nm
• Oregon Green 488 – excitation and emission maxima of 496/524 nm
• Pacific Blue – a violet light excitable dye with an excitation and emission maxima of 410/455 nm
• Texas Red-X – excitation and emission maxima of 595/615 nm
• DSB-X Biotin – Conjugates can be reversibly bound to biotin-binding proteins such as streptavidin or avidin. The concentration (mg/mL) of the DSB-X Biotin-labeled antibody preparation can be determined by measuring the absorbance of the dialyzed sample at 280 nm and dividing this value by 1.3 or 1.4 when measured in solution in a cuvette with a 1-cm pathlength. DSB-X Biotin does not absorb significantly at 280 nm.

For labeling smaller amounts of antibodies (∼100 μg), we recommend our antibody labeling kits. Please review the protein labeling kit user manual for more in depth information, protocols, molecular weights, and degree of labeling for each dye.