Hi

One way to combine search engines outside the MaxQuant environment with
good quantification algorithms is the OpenMS package. This might be a
sensible way to go if you like to combine multiple search eninges and the
TPP search workflow with an alternative open-source quantification engine.
I am not saying that it is the best but it might be worth a shot.

Hannes

On 2 December 2014 at 00:17, Alejandro <[email protected]> wrote:

> Hi Brian,
>
> Of what I have seen XPRESS does indeed performs better than ASAP with high
> resolution data, plus it's incredible fast. Still, there's always the need
> for QC. I also use MaxQuant, specially for multiplex isotopic data, but in
> general one gets much more IDs using Xtandem (or combination of search
> engines with Iprophet, something really helpful) than with Andromeda.
>
> Cheers,
>
> Alejandro
>
> On Monday, December 1, 2014 11:28:51 PM UTC+1, Brian Hampton wrote:
>>
>> It has been my experience that ASAPRatio is slow (haven't used 4.8 yet)
>> and inaccurate even with high mass accuracy data.  I've used both chemical
>> isotopic labeling and SILAC data sets and you really need to QC the
>> results.  The output of ASAPRatio is not to be trusted, based on my
>> experience with it.  I've seen "interesting" hits have a given
>> "interesting" ratio and then go back and look at the peak integrations and
>> have occasionally found that after performing QC on the data that the ratio
>> was reversed from what was originally reported by the algorithm!   This
>> calls into question the accuracy of the entire dataset quantitation as
>> performed by ASAPRatio.
>>
>> The original Aebersold paper on ASAPRatio is demonstrated on a reduced
>> complexity dataset e.g. a pulldown.  The P-value was described as a way to
>> quickly sort changed from unchanged compared to the background.  I am
>> suspicious that ASAPRatio is just not that suited to datasets from complex
>> samples like cell lysates et. al.  which is what I have been using it for
>> and I suspect you have as well.
>>
>> I will begin use of XPRESS and see how that performs.  Given the need for
>> quantification of proteomic data sets, I hope the TPP team is working on a
>> better MS1 quan package than what is currently present in TPP.  It would be
>> nice to see something more robust like Skyline but better suited to shotgun
>> vs targeted quantification.  There is a paper describing ISOQUANT which
>> looks promising but I believe it was originally written to handle SILAC
>> only datasets.  Maybe the TPP developers can obtain this from the author
>> and adapt it to handle multiple isotope labeling strategies and make it
>> available to all their loyal TPP users who have benefited greatly by their
>> efforts to date.
>>
>> Since you have high resolution data, have you tried MaxQuant?
>>
>> Cheers,
>> Brian
>>
>> Brian Hampton
>> Protein Analysis Lab
>> Center for Vascular and Inflammatory Diseases
>> University of Maryland School of Medicine
>> 655 West Baltimore Street BRB 7-018
>> Baltimore  MD  21201
>> V: 410-706-8207
>>
>>
>> On Mon, Dec 1, 2014 at 1:04 PM, Alejandro <[email protected]> wrote:
>>
>>> A quick update.
>>>
>>> After running the same files with TPP 4.8, running time with ASAP ratio
>>> is quite reduced, to ~1h, but quantitation seems to work better with XPRESS.
>>>
>>> Alejandro
>>>
>>> On Wednesday, November 19, 2014 7:29:30 PM UTC+1, Alejandro wrote:
>>>>
>>>> Hi all,
>>>>
>>>> I'm analyzing dimethylated data obtained with a QExactive using
>>>> XTandem! (have tried both static or variable searches). If the data is
>>>> quantified using Xpress, the time it takes is quite normal, ie fast,
>>>> minute(s) or so for a 1GB RAW file (ca. 250MB mzXML), however when
>>>> activating ASAPratio, the processing takes hundred times more than with
>>>> Xpress (which reports a quite disperse distribution of ratios, not seen
>>>> with Orbitrap data, thus the reason to see how ASAP performs). After
>>>> looking in the list I found a post which discussed somehow this
>>>> https://groups.google.com/d/topic/spctools-discuss/Tkko
>>>> HpXAh4A/discussion which was related to multithreading.
>>>>
>>>> When running this analysis the bottleneck seems to come from the
>>>> ASAPratio:
>>>>
>>>> Stucked at:
>>>>
>>>> running: "C:/Inetpub/tpp-bin/XPressPeptideParser "interactasap.pep.xml" 
>>>> -m20 -a -nn,8.04437027 -nK,8.04437027 -H -c5"
>>>> .................................................. 1k
>>>> .................................................. 2k
>>>> .................................................. 3k
>>>> .................................................. 4k
>>>> .................................................. 5k
>>>> .................................................. 6k
>>>> .................................................. 7k
>>>> .
>>>> command completed in 22 sec
>>>>
>>>> running: "C:/Inetpub/tpp-bin/ASAPRatioPeptideParser "interactasap.pep.xml" 
>>>> -lnK -C -r0.02"
>>>>
>>>>
>>>> The same scenario as the one described in the old post seems to happen
>>>> here, only one core and ~50MB usage of RAM, using only
>>>> ASAPRatioPeptideParser.exe and this taking several hours to complete.
>>>>
>>>> Could it be also the mentioned "...redundant disk reads and base64
>>>> decoding due to poor caching of the scans read from mzXML..." the cause? Or
>>>> it is just the nature of the data obtained with the Qexactive that makes it
>>>> take longer? I haven't checked if something would change by using an old
>>>> version of ASAPRatio ~2009 from that post. Though I don't think this would
>>>> be compatible with the current parsers.
>>>>
>>>> Any clues?
>>>>
>>>> Thanks,
>>>>
>>>> Alejandro
>>>>
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