Scorpions™ Probes

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Scorpions™ probes are highly sensitive, sequence–specific, bi-labeled fluorescent probe/primer hybrids, designed for real-time quantitative PCR1-3. Sigma-Genosys is licensed by DxS Ltd to sell Scorpions probes.

Two different molecular structures are available: Scorpions uni-probe, using the hairpin-loop format, and Scorpions bi-probe, using a duplex format.

In both cases, the reaction leading to a fluorescent signal generation is an intramolecular event, which is effectively instantaneous and occurs before any competing side reactions. This enables Scorpions probes to provide stronger signals, shorter reaction times and better discrimination than other conventional bi-molecular mechanisms. It also allows for more reliable probe design.

• Deprotected, desalted and purified by PAGE or RP-HPLC
• Available in lengths of 30 to 60mers (uni-probe) and 15 to 45mers (bi-probe)
• Delivered dried in individual, opaque tubes
• Shipped within 7 to 10 working days of receiving your order, pending successful QC validation

Guaranteed yields of Scorpions probes

Labels for Scorpions probes

Click here for a complete table of product specifications.

How do Scorpions uni-probes work?

The Scorpions uni-probe consists of a single-stranded bi-labeled fluorescent probe sequence held in a hairpin-loop conformation (approx. 20 to 25 nt) by complementary stem sequences (approx. 4 to 6 nt) on both ends of the probe. The probe contains a 5'end reporter dye and an internal quencher dye directly linked to the 5'end of a PCR primer via a blocker. The blocker prevents Taq DNA polymerase from extending the PCR primer. The close proximity of the reporter dye to the quencher dye causes the quenching of the reporter's natural fluorescence.

At the beginning of the real-time quantitative PCR reaction, Taq DNA polymerase extends the PCR primer and synthesizes the complementary strand of the specific target sequence. During the next cycle, the hairpin-loop unfolds and the loop-region of the probe hybridizes intramolecularly to the newly synthesized target sequence. The reporter is excited by light from the real-time quantitative PCR instrument (hγ1). Now that the reporter dye is no longer in close proximity to the quencher dye, fluorescence emission may take place (hγ2). The significant increase of the fluorescent signal is detected by the real-time PCR instrument and is directly proportional to the amount of target DNA.

Why use Scorpions bi-probes?

The Scorpions bi-probe is a duplex of two complementary labeled oligonucleotides, offering stronger signal intensity than the uni-probe structure. One oligonucleotide of the bi-probe is labeled with a 5'end reporter dye and carries both the blocker and PCR primer elements, while the other oligonucleotide is labeled with a 3'end quencher dye. The mechanism of action is then essentially the same as the uni-probe: during real-time quantitative PCR, the 5'end reporter and 3'end quencher dyes are separated from each other leading to a significant increase in fluorescence emission.

Click here for reporters & quenchers available for bi-fluorescent probes.

References
1. Bates, J.A., and E.J.A. Taylor. Scorpions ARMS primers for SNP real-time PCR detection and quantification of Pyrenophora teres. Molecular Plant Pathology 2(5), 275-280, 2001.

2. Hart, K.W., et al. Novel method for detection, typing, and quantification of human Papillomaviruses in clinical samples. J. Clin. Microbiol. 39(9), 3204–12, 2001.

3. Thelwell, N., et al. Mode of action and application of Scorpions primers to mutation detection. Nucleic Acids Research 28(19), 3752-61, 2000.