QXY21 NHS ester [equivalent to QSY-21 NHS ester]

QSY-21 NHS esters (or succinimidyl esters) readily reacts with the primary amines (R-NH<sub>2</sub>) of proteins, amine-modified oligonucleotides, and other amine-containing molecules. The resulting dye conjugates are quite stable.

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Additional ordering information

Telephone	1-800-990-8053
Fax	1-800-609-2943
Email	sales@aatbio.com
Quotation	Request
International	See distributors
Shipping	Standard overnight for United States, inquire for international

Physical properties

Molecular weight	892.90
Solvent	DMSO

Spectral properties

Absorbance (nm)	660
Correction Factor (280 nm)	0.32
Extinction coefficient (cm ^-1 M ^-1)	89000¹

Storage, safety and handling

H-phrase	H303, H313, H333
Hazard symbol	XN
Intended use	Research Use Only (RUO)
R-phrase	R20, R21, R22
Storage	Freeze (< -15 °C); Minimize light exposure
UNSPSC	12352200

Overview SDS Protocol

Molecular weight

892.90

Absorbance (nm)

660

Correction Factor (280 nm)

0.32

Extinction coefficient (cm ^-1 M ^-1)

89000¹

QXY21 is the same molecule to QSY-21 acid (ThermoFisher). QSY-21 has a broad and intense absorption at ~661 nm maxima with no detectable fluorescence, making it useful as an acceptor in fluorescence resonance energy transfer (FRET) applications. It is a common long-wavelength quencher to best pair with Cy5, Alexa Fluor 647, iFluor 647 or other spectrally similar fluorescent dyes.

Calculators

Common stock solution preparation

Table 1. Volume of DMSO needed to reconstitute specific mass of QXY21 NHS ester [equivalent to QSY-21 NHS ester] to given concentration. Note that volume is only for preparing stock solution. Refer to sample experimental protocol for appropriate experimental/physiological buffers.

	0.1 mg	0.5 mg	1 mg	5 mg	10 mg
1 mM	111.995 µL	559.973 µL	1.12 mL	5.6 mL	11.199 mL
5 mM	22.399 µL	111.995 µL	223.989 µL	1.12 mL	2.24 mL
10 mM	11.199 µL	55.997 µL	111.995 µL	559.973 µL	1.12 mL

Molarity calculator

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Mass (Calculate)		Molecular weight		Volume (Calculate)		Concentration (Calculate)		Moles
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Spectrum

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Spectral properties

Absorbance (nm)	660
Correction Factor (280 nm)	0.32
Extinction coefficient (cm ^-1 M ^-1)	89000¹

Product Family

Name	Excitation (nm)	Emission (nm)	Extinction coefficient (cm ^-1 M ^-1)	Quantum yield
XFD488 NHS Ester Same Structure to Alexa Fluor™ 488 NHS Ester	499	520	73000	0.92¹
XFD350 NHS Ester Same Structure to Alexa Fluor™ 350 NHS Ester	343	441	19000	-
XFD532 NHS Ester Same Structure to Alexa Fluor™ 532 NHS Ester	534	553	81000	0.61¹
XFD594 NHS Ester Same Structure to Alexa Fluor™ 594 NHS Ester	590	618	92000	0.66¹
XFD555 NHS Ester Same Structure to Alexa Fluor™ 555 NHS Ester	553	568	155000	0.1¹
XFD647 NHS Ester Same Structure to Alexa Fluor™ 647 NHS Ester	650	671	270000	0.33¹
XFD680 NHS Ester Same Structure to Alexa Fluor™ 680 NHS Ester	681	704	132000	0.36¹
XFD700 NHS Ester Same Structure to Alexa Fluor™ 700 NHS Ester	696	719	205000	0.25¹
XFD750 NHS Ester Same Structure to Alexa Fluor™ 750 NHS Ester	752	776	290000	0.12¹
Cy5DIGE NHS ester	651	670	250000¹	0.27¹, 0.4²
Cy2DIGE NHS ester	492	508	150000	0.120
Cy3DIGE NHS ester	555	569	150000¹	0.15¹
XFD546 NHS Ester Same Structure to Alexa Fluor™ 546 NHS Ester	561	572	112000	0.79¹
XFD568 NHS Ester Same Structure to Alexa Fluor™ 568 NHS Ester	579	603	88000	0.69¹
XFD514 NHS Ester Same Structure to Alexa Fluor™ 514 NHS Ester	518	543	80000	-
QXY7 NHS ester [equivalent to QSY-7 NHS ester]	-	-	90000¹	-
Cy3B NHS ester	560	571	120000¹	0.58¹
Show More (8)

Images

Figure 1. QSY-21 NHS esters (or succinimidyl esters) readily reacts with the primary amines (R-NH₂) of proteins, amine-modified oligonucleotides, and other amine-containing molecules. The resulting dye conjugates are quite stable.

Figure 2. Chemical structure for QXY21 NHS ester [equivalent to QSY-21 NHS ester].

Citations

View all 12 citations: Citation Explorer

A Sensitive Near-Infrared Fluorescent Sensor for Mitochondrial Hydrogen Sulfide
Authors: Ji, A., Fan, Y., Ren, W., Zhang, S., Ai, H. W.
Journal: ACS Sens (2018): 992-997

Imaging intracellular quantum dots: fluorescence microscopy and transmission electron microscopy
Authors: Szymanski, C. J., Yi, H., Liu, J. L., Wright, E. R., Payne, C. K.
Journal: Methods Mol Biol (2013): 21-33

Family of enhanced photoacoustic imaging agents for high-sensitivity and multiplexing studies in living mice
Authors: de la Zerda, A., Bodapati, S., Teed, R., May, S. Y., Tabakman, S. M., Liu, Z., Khuri-Yakub, B. T., Chen, X., Dai, H., Gambhir, S. S.
Journal: ACS Nano (2012): 4694-701

Reversible off-on fluorescence probe for hypoxia and imaging of hypoxia-normoxia cycles in live cells
Authors: Takahashi, S., Piao, W., Matsumura, Y., Komatsu, T., Ueno, T., Terai, T., Kamachi, T., Kohno, M., Nagano, T., Hanaoka, K.
Journal: J Am Chem Soc (2012): 19588-91

Visualizing mechanical tension across membrane receptors with a fluorescent sensor
Authors: Stabley, D. R., Jurchenko, C., Marshall, S. S., Salaita, K. S.
Journal: Nat Methods (2011): 64-7

Pyrenebutyrate Leads to Cellular Binding, Not Intracellular Delivery, of Polyarginine-Quantum Dots
Authors: Jablonski, A. E., Kawakami, T., Ting, A. Y., Payne, C. K.
Journal: J Phys Chem Lett (2010): 1312-1315

A comparative study of the binding of QSY 21 and Rhodamine 6G fluorescence probes to DNA: structure and dynamics
Authors: Kabelac, M., Zim and l, F., Fessl, T., Chval, Z., Lankas, F.
Journal: Phys Chem Chem Phys (2010): 9677-84

Evaluation of glucose sensitive affinity binding assay entrapped in fluorescent dissolved-core alginate microspheres
Authors: Chaudhary, A., Raina, M., Harma, H., Hanninen, P., McShane, M. J., Srivastava, R.
Journal: Biotechnol Bioeng (2009): 1075-85

Dissolved core alginate microspheres as "smart-tattoo" glucose sensors
Authors: Chaudhary, A., Raina, M., McShane, M. J., Srivastava, R.
Journal: Conf Proc IEEE Eng Med Biol Soc (2009): 4098-101

Tumor-specific detection of an optically targeted antibody combined with a quencher-conjugated neutravidin "quencher-chaser": a dual "quench and chase" strategy to improve target to nontarget ratios for molecular imaging of cancer
Authors: Ogawa, M., Kosaka, N., Choyke, P. L., Kobayashi, H.
Journal: Bioconjug Chem (2009): 147-54

References

View all 1 references: Citation Explorer

Synthesis and characterization of a small, membrane-permeant, caspase-activatable far-red fluorescent peptide for imaging apoptosis
Authors: Bullok K, Piwnica-Worms D.
Journal: J Med Chem (2005): 5404