On Tue, 23 Nov 1999, Cynthia Favara wrote:

> Can someone write out the chemical reaction for HRP-AEC-H202. I can find
> lots of generic reactions between substrate and HRP but nothing definite. If
> you could even point me towards the right chemistry text I would be
> grateful.

   So would I. The oldest AEC reference I know is MS Burstone (1960) in
   J Histochem Cytochem 8:63-70. This was a method for cytochrome
   oxidase. It's pre-DAB and long obsolete. RC Graham +2 (1965) may be
   the first published AEC method for peroxidase activity, in J Histochem
   Cytochem 13:150-152. Neither paper provides even a tentative equation
   or a guessed formula for the red oxidation product. A close study
   of the references in these papers might help you in your righteous
   quest. At the very least they might indicate why
   3-amino-9-ethylcarbazole was tested in the first place as a
   chromogen for peroxidases and other oxidoreductases.

 This isn't a helpful reply, but I hope it's a stimulating one. There
 are a few people who Really Know a Lot about Histochemistry, who keep an
 eye on our humble HistoNet questions and answers, but only rarely send
 in an authoritative answer.

                                     John A. Kiernan,
                                     Department of Anatomy & Cell Biology,
                                     The University of Western Ontario,
                                     LONDON,  Canada  N6A 5C1
                                        FAX (Department): (519) 661-3936
                                        E-mail: kiernan@uwo.ca