Thanks David for the reply and for the future work! I will see how the 
comet results turn out and report anything (hopefully) useful.

Best,

Adam

On Tuesday, September 26, 2017 at 5:50:48 PM UTC-5, David Shteynberg wrote:
>
> MASSDIFFMODE should be compatible with most pepXML files from comet and 
> beyond.  The only issue I see with using SpectraST is that the DECOYS are 
> going to be different, so you have to take that into consideration if you 
> are combining SpectraST results with other search engines and have 
> different sets DECOYS sequences then the result should probably not be 
> combined with the NSS model on.  I am working on something that will 
> facilitate the combining of SpectraST results with other search engines.  
> For now however,  you can run iProphet on the SpectraST search results 
> independently.
>
> Cheers,
> -David
>
> On Tue, Sep 26, 2017 at 2:24 PM, Adam R <[email protected] <javascript:>> 
> wrote:
>
>> Thanks David for the tip! I will give MSFragger a try but unfortunately I 
>> will have to wait for MTA authorization. In the meantime, would there be 
>> any limitation to using a comet-generated pep.xml file using a wide-mass 
>> window? Is the MASSDIFFMODE feature compatible with comet? Would there be 
>> any compatibility issues when combining with SpectraST results in iProphet?
>>
>> Best,
>>
>> Adam
>>
>> On Tuesday, September 26, 2017 at 11:00:24 AM UTC-5, David Shteynberg 
>> wrote:
>>>
>>> Hi Adam,
>>>
>>> Yes there is a mode in PTMProphet you can enable called MASSDIFFMODE, it 
>>> will localize the mass difference like a PTM.  I have tried this using 
>>> MSFragger and tier-wise open mass searching using SpectraST.
>>>
>>> -David
>>>
>>> On Mon, Sep 25, 2017 at 11:09 AM, Adam R <[email protected]> wrote:
>>>
>>>> Hi David,
>>>>
>>>> Thank you for the prompt response! I will give it a try from the 
>>>> command line. I also have a follow-up question to ask to this as I have 
>>>> been wondering about other ways to tackle the data. 
>>>>
>>>> Gygi's group published a paper in 2015 (
>>>> http://www.nature.com/nbt/journal/v33/n7/abs/nbt.3267.html) about 
>>>> using wide mass tolerance windows for searching spectra (+/- 500 Da 
>>>> windows) to identify modifications in unassigned spectra. They went on to 
>>>> use the Ascore algorithm to identify the sites of modifcation. I'm 
>>>> wondering whether this would be possible to perform with the current 
>>>> iteration of TPP? (i.e. wide mass tolerant search with comet followed by 
>>>> site analysis by PTM Prophet) PTM Prophet's input requires the amino acid 
>>>> and the mass shifts for PTMs but I'm wondering whether it could be 
>>>> utilized 
>>>> to identify "un-specified" mods on any amino acid. 
>>>>
>>>> Best,
>>>>
>>>> Adam
>>>>
>>>> On Monday, September 25, 2017 at 11:47:39 AM UTC-5, David Shteynberg 
>>>> wrote:
>>>>>
>>>>> There are a couple things wrong here.  Primarily there is a bug in 
>>>>> current distributed version of PTMProphet that prevents it from being run 
>>>>> through the web-interface.  There is already a fix available, however, 
>>>>> you 
>>>>> will probably want to run this from the command line because of reasons 
>>>>> that follow.  Your command needs some adjustment.  As is it will try to 
>>>>> localize a different "PTM" on the amino acids you have specified for each 
>>>>> set of amino acids, when what you want it to localize on any amino acid.  
>>>>> You can try the following in a command terminal
>>>>>
>>>>> cd c:\TPP\data\[YOUR_DATA_DIRECTORY]
>>>>>
>>>>> PTMProphetParser MZTOL=0.2 ABCDEFGHIJKLMNOPQRSTUVXWYZ:639.3169 
>>>>> [YOUR_INPUT_PEPXML] [YOUR_OUTPUT_PEPXML]
>>>>>
>>>>>
>>>>> Thank you for reporting the issue.
>>>>>
>>>>> -David
>>>>>
>>>>>
>>>>> On Sun, Sep 24, 2017 at 11:19 AM, wicher89 <[email protected]> wrote:
>>>>>
>>>>>> Hi Everyone,
>>>>>>
>>>>>> I am analyzing peptides from cells that have been treated with a UV 
>>>>>> crosslinker attached to a small molecule (ABPP method). This results in 
>>>>>> mono-linked peptides. Because the UV cross-linker is not residue 
>>>>>> specific, 
>>>>>> I am forced to search the data in comet with a modification of 639.3118 
>>>>>> Da 
>>>>>> on any amino acid other than those with fixed modifications. I am able 
>>>>>> to 
>>>>>> process the output files until the iProphet step, but am running into 
>>>>>> command failure at PTM Prophet. Is there a maximum limit on the number 
>>>>>> of 
>>>>>> amino acids used at once in a single line entry for a modification? I 
>>>>>> have 
>>>>>> attached screenshots of the parameters used and the command failure 
>>>>>> output.
>>>>>>
>>>>>> Thanks!
>>>>>>
>>>>>>
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