Hello TPP,

I'm a new TPP user, and so far, very happy with the results from
simple qualitative proteomic experiments (information dependent
acquisitions and straight database searching). I am know going to
start some quantitative experiments using light and heavy
dimethylation labeling reactions (D-labeled formaldehyde and sodium
cyanoborohydride). I've already read many of the discussion threads on
this topic, so I guess both XPRESS and/or ASAPratio should work fine
in this context. I also read about the way to perform the DB searches
using the static and variable modificatios too :-).

I have though a couple of questions before I start processing my
samples (whole cell lysate digests and subcelular fractions).

1. At this time, I only have available for my analysis a AB QTRAP 3200
system. Previously, I have worked with this system and analyzed my
data (same labeling approach) using Mascot Distiller program-Rover
combo. In those conditions, Mascot Distiller gave me the possibility
of doing the quantitation on the full MS scan or on what Distiller
called the zoom scan, which is the ER (enhanced resolution) scan done
on the trap an lower scar rates to determine the charge and 'exact'
mass of the precursor. I have gone through the XPRESS and ASAPratio
parameters, and this option doesn't seem available. Could somebody
tell me whether this option is available, or whether the
quantification will be done on the full MS data by default?

2. Occasionally, I fractionate my samples (after digestion and
labelling) by SCX, and then inject each fraction into the MS (ONE Wiff
file, with X number of samples as fractions present). When I analyzed
these data with Mascot Distiller, I run into some problems, specially
for those peptides which coeluted into more than one fraction during
the SCX separation. Since the same peptide appeared in more than one
fraction, Mascot Distiller was not able to correctly extract the
signals from the individual samples (fractions) and quantitation was
hampered. I was wondering if anyone has done these type of
experiments, and whether TPP (with either XPRESS or ASAPratio) can
manage this typo of files (One wiff, with multiple sample files, or
multiple wiff files acquired independently)?

Thanks TPP people, looking forward to for your suggestions and
hopefully will move our MS analytical platform to TPP in the near
future.

Alejandro Cohen



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