Scott
There are a few issues that may come up...
1) the 1/3 rule: if the parents are getting over 1000 you may miss the fragments that are
below 1/3 the parent mass.
2) i often get nice results by looking at the full scan data from triple play runs...then
the 1/3 rule does not come into play...glycopeptides are often labile and loose frags that
form the marker ions without ms/ms...these often show up at low intensity in the full
scan/normal tune...but what if you also crank up the source temp/gas/apicid/tubelens (any
of these) and try to bake the glyopeptides a bit to induce them to fall off...then put up
a trace in Qualbrowser for the sum of the marker ions...it works for me.
3)I have seen some of the larger glycopeptides just loose a little piece without forming a
very large marker ion set under ms/ms...but in full scan ms you can actually see
several...maybe it is the 1/3 rule in action...
Matt Sweeney
mattsweeney@earthlink.net
Mass Spec Consulting
Training/Operations/Consulting/Method Development
LC/MS Pharmacokinetics, Peptides, Proteins, Metabolism,
Maintenance Classes, Specialist in Finnigan Equipment and Software
-----Original Message-----
From: Scott Borneman <sborneman@epicyte.com>
To: Recipients of ABRF List <abrf@aecom.yu.edu>
Date: Monday, March 05, 2001 8:47 AM
Subject: LCQ Deca-Glycan MS
>I have recently been trying to detect glycan signals on Finnican LCQDeca
>from antibody tryptic glycopeptides. I am using either a "triple play"
>experiment or looking at ms/ms of the top 3-5 parent ions from each scan
>(both which are tuned for peptide fragmentation). I am relatively new at
>looking specifically for the carbohydrate ions an was hoping someone could
>give some advice on to the appropriate LCQ settings to optimize for
>carbohydrates. I typically cannot find the appropriate mass peak for the
>hexoses or sialic acids.
>
>
>
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