Another very useful technique for determination of oligomers is analytical
ultracentrifugation. Contact the MIRG on the ABRF website for more
information on this technology.
--------------------------------------------------------
Gordon Alton, Ph.D.
Analytical/Protein Chemistry and Mass Spectrometry
Signal Pharmaceuticals Inc.
5555 Oberlin Drive
San Diego, CA 92121
Email: galton@signalpharm.com
Phone: 858-558-7500 x8252
Fax: 858-623-0870
WWW: http://www.electriciti.com/signal/
<http://www.electriciti.com/signal/>
-------------------------------------------------
-----Original Message-----
From: Ioannis A. Papayannopoulos [mailto:ioannis_papayannopoulos@yahoo.com]
Sent: Friday, April 14, 2000 5:18 AM
To: Recipients of ABRF List
Subject: Re: MALDI: Protein dimmer
The dimer is most likely a result of MALDI mass spectrometry analysis, and
commonly observed for proteins, especially in concentrated samples.. You
were correct in trying to find the triply charged dimer peak; it's absence,
although not constituting conclusive proof, would support the notion that
the dimer is, indeed, formed in the mass spectrometer during ionization.
However, as far as I know, short of doing size exclusion chromatography (or,
perhaps, non-denaturing PAGE) you can not say with absolute certainty that
the dimer is, indeed, a feature (aka artifact) of mass spectrometry.
Ioannis Papayannopoulos
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