Re: FITC vs Alexa 488

From: Howard T Petrie (h-petrie@ski.mskcc.org)
Date: Thu Mar 21 2002 - 17:21:32 EST


Well, unless you do a direct comparison (who's got that much antibody
to waste?) it's hard to make more than an empirical judgement.  I've
made some dozens of A488 conjugates, and I would have to say that by
flow, it's definitely brighter, but my estimate would be on the order
of 2-4X.  Using mercury excitation on a fluorescent microscope,
however, it's quite substantially brighter than FITC.  So overall, I
would say the claims are reasonable.  We like the Alexa series very
much.  I have no financial association with Molecular Probes (except
that I buy their products.  Lots of them.).  HTP

>On Molecular Probes' website are claims that Alexa 488 is 6-7 times brighter
>than FITC. Preliminary evidence from our conjugations of the same antibody
>with FITC or Alexa 488 indicate no advantage from using Alexa 488. Can
anyone who compared Alexa 488 and FITC share their findings?
--


Howard T. Petrie, Ph.D.
Head, Laboratory of Developmental Immunology
Memorial Sloan-Kettering Cancer Center
Box 341, 1275 York Avenue
New York, NY 10021
phone (212)639-2149
fax (212)794-4019



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