tandem dyes

From: James Marvin (jmarvin@flowcity.bsd.uchicago.edu)
Date: Tue Oct 29 2002 - 14:43:24 EST


Hello,

1.  Is the extinction coefficient for most dyes such that in a PE-Cy7
tandem the Cy7 will not be able to be excited by the 633 laser because it
has not had time to return to its resting state?
Theoretically this problem should not have to be addressed, I think.  While
reading Mario's webstie on tandems he stated that Cy7 in a PECy7 tandem
will also be excited by the 633 laser.  Even if you can do interlaser
compensation, how could you separate the signal from  PECy7  and a regular
Cy 7 molecule on the same cell.  In other words if a tandem is emitting Cy7
fluorescence that was not excited by the PE, how do you separate this
signal from a Cy7 alone antibody.

2.  We have seen a lot of PE signal from an antibody stained with
PECy7.  Is this a poorly conjugated fluorochrome?  Does this mean that you
will have more Cy7 emitting independent of PE excitation?  Is this
phenomenon common with tandems?    Compensation?  Seems straightforward if
you have another PE antibody that is bright.  But what if its not?

3.Are there many of you out there making your own tandems?

I guess a lot of these question are addressing the art of setting up
multicolor experiments.  Apparently its not quite as easy as looking at
stokes shifts huh.
Thanx in advance,   marv



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