Eurogentec is a licensed supplier of Molecular Beacons, and offers a large number of fluorescent reporters and quenchers.
- Purification : double-HPLC
- Quality Control : HPLC and MALDI-TOF MS.
- Maximum length : standard Molecular Beacons with a 3’ DABCYL is 50 bases.
- Format : Molecular Beacons are provided lyophilized in individual tubes.
We can determine the signal-to-noise ratio (STNR) for each Molecular Beacons upon request. The STNR is determined by hybridizing Molecular Beacons to its complementary sequence and comparing fluorescence to background. For FAM labelled Molecular Beacons, the STNR should be > 15. All other dyes require a signal-to-noise ratio > 10.
Molecular Beacons Principle
Molecular Beacons are probes which contain a stem-loop structure, a fluorophore and a quencher at their 5’ and 3’ ends, respectively.
The ‘stem’ sequence keeps the fluorophore and the quencher together, but only in the absence of a sequence complementary to the ‘loop’ sequence (1). As long as the fluorophore and the quencher are in close vicinity, any photons emitted by the fluorophore are absorbed by the quencher.
In the presence of a complementary sequence (2), the probe unfolds and hybridizes to the target. The fluorophore is displaced from the quencher, which can no longer absorb the photons emitted by the fluorophore. As a result the probe starts to fluoresce. The amount of signal is proportional to the amount of target sequence, and is measured in Real-Time to allow quantification of the amount of target sequence.