UBQ-2 NHS Ester

Unit Size
Price (USD)
Cat.#: 1741-5
Unit size: 5 mg
in stock
Cat.#: 1741-25
Unit size: 25 mg
in stock
Cat.#: 1741-100
Unit size: 100 mg
in stock

Universal Black 2 Quencher (UBQ-2, Black Hole Quencher®-2 (BHQ®-2) equivalent) is a dark quencher with no native emission due to the polyaromatic-azo backbone. This nonfluorescent acceptor is often the quencher of choice for qPCR probes and for other fluorescence-quenched probe applications. A broad and intense quenching range from 560-670 nm makes it useful as an acceptor in fluorescence resonance energy transfer (FRET) applications in conjunction with orange to far-red emitting dyes such as Cy3, Cy5, ROX, Texas Red, Alexa Fluor® 546, 555, 594, 633, 647, and IRDye® 650.

The NHS ester (or succinimidyl ester) is the most popular amine reactive group for labeling with the primary amines of proteins (Lys), amine-modified oligonucleotides, and other amine-containing molecules. The labeling occurs most efficiently at pH 7-9 and forms a stable, covalent amide bond.

Primary amine
Abs maximum
580 nm
Extinction coefficient
38,000 cm-1M-1
Spectrally compatible dyes
Cy3, Cy5, ROX, Texas Red, Alexa Fluor® 546, 555, 594, 633, 647, IRDye® 650
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

Black Hole Quencher® is a registered trademark of LGC Biosearch Technologies Inc.