IR 680LT Maleimide

Unit Size
Price (USD)
Cat.#: 1527-1
Unit size: 1 mg
in stock
Cat.#: 1527-5
Unit size: 5 mg
in stock
Cat.#: 1527-25
Unit size: 25 mg
in stock
Cat.#: 1527-100
Unit size: 100 mg
in stock

IR 680 (IRDye® 680 equivalent) is a bright, water-soluble dye that is structurally very similar to the commonly used Cy®5.5 Dye. The water solubility, brightness, and self-quenching characteristics of this dye were significantly improved by the introduction of two additional sulfo groups. Far-red fluorescent IR 680 conjugates are spectrally similar to other 680 nm dyes that are used for flow cytometry, microscopy and other applications. Proteins can be labeled with IR 680 at high molar ratios without significant self - quenching, leading to brighter conjugates and more sensitive detection.

Maleimide is the most popular sulfhydryl-reactive reactive group for conjugating the dye to a thiol group on a protein, oligonucleotide thiophosphate, or low molecular weight ligand. The maleimide group specifically and efficiently reacts with reduced thiols (sulfhydryl groups, –SH) at pH 6.5 to 7.5 to form stable thioether bonds.

Thiol (Cys)
Abs/Em Maxima
679/694 nm
Extinction coefficient
190,000 cm-1M-1
Water, DMSO, DMF
Spectrally similar dyes
Alexa Fluor® 680, DyLight® 680, IRDye® 680
Molecular weight
Storage conditions
Shipping conditions
Ambient temperature


Enter only one — either volume or amount of protein to be labeled
Enter only one — either maximum concentration of DMSO or volume DMSO added to label

IRDye® is a trademark of LI-COR Biotechnology.