Date: Fri, 17 Jan 1997 17:55:37 +0000 (GMT)
From: KNIERMAN MICHAEL D <KNIERMAN_MICHAEL_D@Lilly.Com>
Subject: MS/MS of phosphorylated peptide
To: Recipients of ABRF List <abrf@aecom.yu.edu>
I was wondering if anyone have experience in the analysis of
phosphorylated peptides by MS/MS. We have a peptide that we believe is
phosphorylated and performed nanospray positive ion MS/MS on a triple
quadrapole instrument. We know the mass of the base peptide and the mass
of this particular fraction was +80 Da. The MS/MS spectra of this fraction
matched better if a dehydroalanine was substituted for the supposed
phosphorylated ser residue. I also had a peak in the MS/MS spectra that
was not assignible to the peptide but was -80 Da from the selected ion for
MS/MS after charge state correction(+2). However I was not able to see a
peak at 80 Da. in the MS/MS spectra. Has anyone seen the phosphate group
behave this way in MS/MS? Could it be a sulfate adduct? Any comments would
be appreciated.
Michael D. Knierman
Eli Lilly
knierman@lilly.com
Disclaimer: Any opinions stated above are my opinion and do not reflect any
position of Eli Lilly and Co.