[Histonet] Re: Methanol in H2O2 explanation

[Rene J Buesa]

This is the real explanation.
Mind that the title refers to erythrocyte pseudoperoxidase inhibition and in the title of the article is the procedural sequence:
1- fix the blood smear with methanol, which is the standard procedure, and
2- apply H2O2 to quench the peroxidase activity.
René J.


________________________________
From: C.M. van der Loos <c.m.vanderloos <@t> amc.uva.nl>
To: "histonet netserver (histonet <@t> lists.utsouthwestern.edu)" <histonet <@t> lists.utsouthwestern.edu> 
Sent: Thursday, July 12, 2012 1:23 PM
Subject: [Histonet] Re: Methanol in H2O2 explanation

Hi,

There is a paper from 1972 (!) by Streefkerk entitled: "Inhibition of erythrocyte pseudoperoxidase activity by treatment with hydrogen peroxidase following methanol. JHC 30:504. So perhaps the origin of methanol is not that mysterious.

I cannot imagine that methanol is still considered for cryo's when performing IHC: it certainly kill many epitopes!



Cheers, Chris



Chris van der Loos

Academic Medical Center

Dept. of Pathology

Amsterdam

The Netherlands



Date: Wed, 11 Jul 2012 20:22:38 +0200
From: "Gudrun Lang" <gu.lang <@t> gmx.at>
Subject: [Histonet] Re: Methanol in H2O2 explanation
To: <histonet <@t> lists.utsouthwestern.edu>
Message-ID: <000f01cd5f92$271cb870$75562950$@gmx.at>
Content-Type: text/plain;      charset="iso-8859-1"

Ha! I've found it. It can be found in Dr. Kiernan's book in the chapter
enzymehistochemistry - the thing, that an electron-donator is used for
demonstration.
And he states, that methanol alone also inhibits peroxidase - perhaps by
the fixation = denaturation effect on the protein?

In the following publication one can see the equations for the
peroxidase-reaction and this phrase:
"In this study, we have used a steady state kinetics approach to demonstrate
that MPO is irreversibly inactivated by excess H2O2 in the absence of
reducing substrate."
The Open Enzyme Inhibition Journal, 2009, 2, 28-35 Mechanism-Based
Inhibition of Myeloperoxidase by Hydrogen Peroxide: Enhancement of
Inactivation Rate by Organic Donor Substrates

It's rather exhausting to prove the own statements  ;-) puh.

Gudrun


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