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
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
