Calman Prussin said-
>In my experience all FITCs (and PEs) are equal, however all
>fluoresceins are not equal.
>
>The MolProbes catalog lists the conjugate as "fluorescein labeled
>dextran", not FITC. My guess is they used FSX, fluorescein-x
>succinimidyl ester, which has a longer wavelength emission and hence
>requires more compensation.
Dave Coder said-
>Also relevant, is the observation of the effect of emission difference on
>compensation that Joe Trotter illustrated some time back. See the
>FITC/Fluorescein Alert! at:
>
>http://facs.scripps.edu/cd4fitc.html
Thanks for these pointers. It was sloppy of me not to have noted that I was
using fluorescein dextran, some in the lab routinely refer to it as FITC
dextran. However, I hadn't appreciated the difference in emission spectra
between FITC and fluorescein, so I have learnt something.
Nevertheless, I noted a similar problem using an out-of-date conjugated
sheep anti-mouse, and I have checked- it is definitely a FITC conjugate. As
I said, it seems to stain the cells brightly enough and gives a good FL1
signal, but also emits strongly in FL2. Is this a known effect of
deterioration of FITC conjugates over time?
______________________________________________
Dr William Smith
Institute for Child Health Research
(Company Limited by Guarantee ACN 009 278 755)
Subiaco, Western Australia, 6008
PO Box 855 West Perth WA 6872
Ph 61 8 9340 8792/8388, Fax 61 8 9388 3414
email williams@ichr.uwa.edu.au
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