questions about the observation of (M-91) ions on AB 4800 MALDI TOF/TOF

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Haixia
Proton Member
Proton Member
Posts: 1
Joined: Thu Jun 06, 2013 9:38 am

questions about the observation of (M-91) ions on AB 4800 MALDI TOF/TOF

Postby Haixia » Thu Jun 06, 2013 9:52 am

Hello all,

I am a new comer to this group, and I hope I can get some discussions related to an observation we recently had on a AB 4800 MALDI TOF/TOF for peptide analysis, we are analyzing a plant peptide with sequence YCRHPSS (in which C is carbamidomethyled), I used 2kv MSMS with CID gas on, and oberved a strong (precursor-91)+ ion in the MSMS spectrum. It's hard to explain as Y usually loses 107 (arometic ring) during fragmenation, does anyone have ever observed similar phenomenon? any suggestions/comments will help. Thank you in advance.

Haixia

botte
Phosphoserine Member
Phosphoserine Member
Posts: 20
Joined: Mon Apr 29, 2013 11:47 pm

Postby botte » Thu Aug 08, 2013 11:49 pm

Dear Haixia,
quick question - is this ion properly resolved to isotopes, or is it a braoder signal? In the latter case it might be a case of metastable decay, which will not necessarily appear at the correct mass I think.
Christof


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