Re: Reduction of Met-O revisited...

From: Marcus Macht (Marcus.Macht@uni-koeln.de)
Date: Tue Aug 01 2000 - 06:42:56 EDT


At 09:51 28.07.00 -0700, you wrote:
>Marcus,
>the Delta Mass list on the ABRF web page
>
>http://abrf.org/ABRF/ResearchCommittees/deltamass/deltamass.html
>
>lists 76 as the molecular weight increase with a beta mercaptoethanol
>adduct can you get adduction of the cysteine with the
>N-methylmercaptoacetamide?
>
>Deb McMillen

Dear Deb,

in principle it should be possible to get an adduct between
N-methylmercaptoacetamide and cystein because NMMA has a free thiol group
(HS-CH2-C(O)-NH-CH3) (albeit I have not observed it so far). But this would
yield in a mass increase of 103 Da in comparison to the observed 75 Da.
Furthermore this modification should be sensitive to DTT addition since it
would be linked via a SS-bond.
The only way I presently could explain this mass shift would be by a
reductive cleavage in the NMMA's amide bond which I assume as very unlikely.

Yours sincerely,
Marcus
**************************************************************
Dr. Marcus Macht
University of Cologne
Centre for molecular medicine - Service laboratory
Joseph-Stelzmann-Str. 52
50931 Cologne, Germany
Tel.: +49 221 478-6995
Fax: +49 221 478-6977
e-mail: Marcus.Macht@uni-koeln.de
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