TaqMan

Source: Wikipedia, the free encyclopedia.

TaqMan probes are

Hoffmann-La Roche for diagnostic assays and by Applied Biosystems (now part of Thermo Fisher Scientific
) for research applications.

The TaqMan probe principle relies on the 5´–3´

quantitative PCR methods, the resulting fluorescence signal permits quantitative measurements of the accumulation of the product during the exponential stages of the PCR; however, the TaqMan probe significantly increases the specificity of the detection. TaqMan probes were named after the videogame Pac-Man (Taq Polymerase + PacMan = TaqMan) as its mechanism is based on the Pac-Man principle.[3]

Principle

TaqMan probe chemistry mechanism

TaqMan probes consist of a fluorophore covalently attached to the 5’-end of the oligonucleotide probe and a quencher at the 3’-end.[4] Several different fluorophores (e.g. 6-carboxyfluorescein, acronym: FAM, or tetrachlorofluorescein, acronym: TET) and quenchers (e.g. tetramethylrhodamine, acronym: TAMRA) are available.[5] The quencher molecule quenches the fluorescence emitted by the fluorophore when excited by the cycler’s light source via Förster resonance energy transfer (FRET).[6] As long as the fluorophore and the quencher are in proximity, quenching inhibits any fluorescence signals.

TaqMan probes are designed such that they anneal within a DNA region amplified by a specific set of primers. (Unlike the diagram, the probe binds to single stranded DNA.) TaqMan probes can be conjugated to a minor groove binder (MGB) moiety, dihydrocyclopyrroloindole tripeptide (DPI3), in order to increase its binding affinity to the target sequence; MGB-conjugated probes have a higher melting temperature (Tm) due to increased stabilization of van der Waals forces. As the

quantitative PCR thermal cycler
is directly proportional to the fluorophore released and the amount of DNA template present in the PCR.

Applications

TaqMan probe-based assays are widely used in

medical laboratories
:

See also

Notes and references

  1. PMID 1871133
    .
  2. ^ TaqMan Gene Expression - NCBI Projects
  3. ^ The Real-Time TaqMan PCR and Applications in Veterinary Medicine - From PacMan to TaqMan - a computer game revisited Archived 2009-05-05 at the Wayback Machine
  4. ^ TaqMan Probes: Introduction, functioning and applications
  5. PMID 10606668
    .
  6. PMID 11013345
    .
  7. ^ AlleleID - Assay Design for Bacterial Identification

External links

1. TaqMan RT-PCR resources- primer databases, software, protocols Archived 2010-11-25 at the Wayback Machine
2. Beacon Designer - Software to design real time PCR primers and probes including SYBR Green primers, TaqMan Probes, Molecular Beacons.

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