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e-oligos Oligo Dilution Calculator
Oligo Dilution Calculator
Example of font and layout for font class "subtitle":Real Time Quantitative Detection Probes: Molecular Beacons
Example of font and layout for font class "subsubtitle": Real Time Quantitative Detection Probes: Molecular Beacons
Example of font and layout for font class "greytext":Real Time Quantitative Detection Probes: Molecular Beacons
Example of font and layout for font class "smalltext": Real Time Quantitative Detection Probes: Molecular Beacons
This is an example of the font face, size and color to select. 1. Prepare two tubes containing 50 µl of 200 nM molecular beacon dissolved in
3.5 mM MgCl2 and 10 mM Tris-HCl, pH 8.0 and add the oligonucleotide
target to one of the tubes at a final concentration of 400 nM.
Molecular beacons are oligonucleotide probes that can report the presence of
specific nucleic acids in homogenous solutions (Tyagi S, Kramer FR. Molecular
beacons: probes that fluoresce upon hybridization, Nature Biotechnology 1996;
14: 303-308.) They are useful in situations where it is either not possible or
desirable to isolate the probe-target hybrids from an excess of the
hybridization probes, such as in real time monitoring of polymerase chain
reactions in sealed tubes or in detection of RNAs within living cells. Molecular
beacons are hairpin shaped molecules with an internally quenched fluorophore
whose fluorescence is restored when they bind to a target nucleic acid (Figure
1). They are designed in such a way that the loop portion of the molecule is a
probe sequence complementary to a target nucleic acid molecule. The stem is
formed by the annealing of complementary arm sequences on the ends of the probe
sequence. A fluorescent moiety is attached to the end of one arm and a quenching
moiety is attached to the end of the other arm. The stem keeps these two
moieties in close proximity to each other, causing the fluorescence of the
fluorophore to be quenched by energy transfer. Since the quencher moiety is a
non-fluorescent chromophore and emits the energy that it receives from the
fluorophore as heat, the probe is unable to fluoresce. When the probe encounters
a target molecule, it forms a hybrid that is longer and more stable than the
stem and its rigidity and length preclude the simultaneous existence of the stem
hybrid. Thus, the molecular beacon undergoes a spontaneous conformational
reorganization that forces the stem apart, and causes the fluorophore and the
quencher to move away from each other, leading to the restoration of
fluorescence.
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