On Thu, 18 Mar 1999, tylee wrote:

> ... searching the Probes web site, I found a structure for the first 2
>  Alexa dyes I looked for at http://www.probes.com/servlets/structure?item=10169 and
>  http://www.probes.com/servlets/structure?item=10168

  You're quite right; the formulae for the other "Alexa" labels
  are also there if you dig around deeply enough. I wrongly said
  that Mol. Probes were keeping it secret.  However, the use
  of a single trade-name is confusing because these are quite
  different compounds, named apparently from their absorption
  maxima. For example, Alexa 488 is a substituted rhodamine,
  and Alexa 350 and 430 are coumarin derivatives. 
 
 John A. Kiernan,
 Department of Anatomy & Cell Biology,
 The University of Western Ontario,
 LONDON,  Canada  N6A 5C1
   Phone: (519) 679-2111
   FAX (Department): (519) 661-3936
   E-mail: kiernan@uwo.ca