PURETIME ® fluorescence polarization
PURETIME® dyes have characteristically long fluorescence lifetimes. This makes them interesting as fluorescence polarization probes. Short lifetime fluors such as fluorescein, Rhodamine, Alexa, BODIPY or cyanine dyes produce highly polarised emission when attached to even modest sized biomolecules. PURETIME® dyes do not emit highly polarised fluorescence until they are either in highly viscose environments or attached to proteins that rotate slowly in solution.
Applications
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Measure changes in molecular weight at more than 40,000 Da |
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Measure changes in viscosity at more than 400 mPa.s |
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Discriminate against elastic scatter and reflection in challenging assay situations |
Polarization characteristics
As an example, the figures below compare the fluorescence polarization of PURETIME® 22 with fluorescein under similar conditions. All polarization measurements were performed with a BMG Fluostar platereader equipped with a polarising optical fibre head.
Perrin equation plot showing intercept at Pzero=400mP
Perrin equation plot showing intercept at Pzero=450mP
Although the two dyes have similar Pzero values, PURETIME® 22 doesn't plateau until attached to much higher molecular weight molecules as the Perrin equation plot shows below:
Perrin equation plot showing increased measurement window for PURETIME22