[Histonet] Sorry, not the same RE: Complete Endog peroxidase blocking

Gayle Callis gcallis <@t> montana.edu
Mon Jul 25 09:46:14 CDT 2005

The DAKO Dual Block for HRP and Alk phos is NOT the same as the Glucose 
oxidase method.  Glucose oxidase method is based on glucose oxidase + 
glucose = a slow steady release of hydrogen peroxide that interacts with 
the endogenous peroxidases and pseudoperoxidases in the tissues to knock 
them out.  This is a mixture of these two components in a buffer containing 
a slight amount of sodium azide and the sections are incubated in this for 
1 hour in a water bath at 37C.  This block does NOT affect or kill 
endogenous alkaline phosphatase.

The DAKO Dual blocker is probably the same as KPL Universal Block, a lovely 
ready to use reagent.  I think it is one of the ways to block according to 
Jules Elias's list in his book.

  At 02:17 PM 7/24/2005, you wrote:
>I had a particularly difficult time quenching endogenous peroxidase in
>sputum cytopreps full of granulocytes and it was suggested that I try the
>new DAKO Dual Block for HRP and Alk.Phos. and it worked a charm, don't know
>what's in it (proprietary you know), but perhaps it is similar to Gayles
>reagents for glucose oxidase blocking.

Gayle Callis
Research Histopathology Supervisor
Veterinary Molecular Biology
Montana State University - Bozeman
PO Box 173610
Bozeman MT 59717-3610
406 994-6367 (lab with voice mail)
406 994-4303 (FAX)

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