Onyx Quencher™ – Frequently Asked Questions (FAQs)

What is the molecular weight of OQ™?
The molecular weights of OQA, OQB, OQC, and OQD are 518.6, 589.6, 582.6, and 650.7, respectively.

Is the molecular structure of OQ available?
No, structures of the OQ derivatives are proprietary to Sigma and therefore are not available for distribution.

Is OQ available as an internal modification?
No, OQ is only available on the 3’ ends of Custom Primers, Dual-Labeled Probes, and Molecular Beacons.

What is the difference between OQ and TAMRA?
OQ is a dark quencher that releases heat instead of light upon excitation, whereas TAMRA™ is a fluorescent reporter dye. While TAMRA generally works well with FAM, its fluorescence can lead to poor signal-to-noise ratios depending on the nature of the assay.

How should I store OQ-labeled oligos and probes?
OQ-labeled oligos and probes ship dry (and in amber tubes (plates are not amber) for probes to prevent photodegradation of the reporter dye) and should be stored at -20°C. When ready for use, prepare a 100 µM stock solution by resuspending in a weak buffer such as TE (10 mM Tris, pH 7.5 - 8.0, 1 mM EDTA, diluted from buffer solution, Product No. T9285), or for applications in which TE is not suitable, sterile nuclease-free water (Product No. W4502) is a good choice (high-grade water may be slightly acidic and is not recommended for long-term storage, though). To prevent degradation, minimize exposure of probes to light and avoid free-thaw cycles by preparing single-use aliquots; store at -20°C.