Black Hole Quenchers (BHQ)
BHQ dyes are robust dark quenchers that are compatible with ammonium hydroxide deprotection, exhibit excellent coupling efficiencies, have large extinction coefficients and are completely non-fluorescent. Their absorbances are well-tuned to quench a variety of popular fluorophores.
We are happy to offer several products containing the BlackBerry Quencher (BBQ-650), which exhibits a broad absorption profile from 550nm to 750nm, centered at 650nm. This range offers more effective quenching of some of our popular long wavelength dyes like TAMRA, Redmond Red, Cy dyes and DyLight dyes.
The Eclipse quencher from ELITechGroup solves most of the problems inherent in the synthesis of molecular beacon and FRET probes. The Eclipse molecule is highly stable and can be used safely in all common oligo deprotection schemes. The absorbance maximum for Eclipse Quencher is at 522 nm, compared to 479 nm for dabcyl. In addition, the structure of the Eclipse Quencher is substantially more electron deficient than that of dabcyl and this leads to better quenching over a wider range of dyes, especially those with emission maxima at longer wavelengths (red shifted) such as Redmond Red and Cyanine 5. In addition, with an absorption range from 390 nm to 625 nm, the Eclipse Quencher is capable of effective performance in a wide range of colored FRET probes.
CDPI3 MGB™ Labeling
The simplest approach to MGB probe design is to use an MGB support, add a quencher molecule as the first addition and complete the synthesis with a 5’-fluorophore. Alternatively, a fluorophore support could be used with the 5’ terminus containing a quencher molecule followed by a final MGB addition at the 5’ terminus. Glen Research offers 5’-CDPI3 MGB™ Phosphoramidite and 3’-CDPI3 MGB™ CPG.
A molecular beacon probe1 has its natural fluorescence quenched in solution unless it is hybridized to the target sequence. Consequently, the design of a molecular beacon requires a fluorophore to be in one part of the sequence and the quencher molecule to be in another, with both molecules being separated from the oligonucleotide by a hydrocarbon spacer. The Dabcyl group has been found to be a universal quencher. 3’-Dabsyl CPG and 3’-Dabcyl CPG are used to prepare probes with the quencher blocking the 3’-terminus. 5’-Dabcyl Phosphoramidite locates the quencher at the 5’-terminus and Dabcyl-dT places it within the sequence, leaving the 3’-terminus available for polymerase extension.