Universal Black 3 Quencher (UBQ-3, Black Hole Quencher®-3 (BHQ®-3) equivalent) is a dark, far-red nonfluorescent acceptor dye with no native emission. UBQ-3 is often used as an acceptor for preparation of fluorogenic dual-labeled probes, qPCR probes, and for other fluorescence-quenched probe applications. A broad and intense quenching range from 620-730 nm makes it useful as an acceptor in fluorescence resonance energy transfer (FRET) applications in conjunction with far-red to near-IR emitting dyes such as Cy5, Cy5.5, Alexa Fluor® 633, 647, 700, IRDye® 650, 680 and 700.
UBQ-3 is structurally identical to BHQ®-3.

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.


Unit Size5 mg, 25 mg, 100 mg
Primary amine
Abs/Em Maxima615 nm
Extinction coefficient40,700 cm-1M-1
SolubilityDMSO, DMF
Spectrally similar dyesCy5, Cy5.5, Alexa Fluor® 647, 680, 700, IRDye® 650, 680, 700
Molecular weight664.76
Storage Conditions-20°C.
Shipping ConditionsAmbient temperature

Abs/Em Spectra

Protein Labeling Calculator


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