Hello Pete,

I think the answer to your first question is it depends on the specifics of
your analysis.

You can pass iProphet files through iProphet again, since it will just use
the PeptideProphet probabilities which are not modified (only reported) by
iProphet.  If the iProphet is from a single search engine this should be
just fine.  However, if the iProphet file contains results from multiple
search engines then you probably don't want to combine it with iProphet
again as in this case each spectrum search result comes from the highest
scoring search engine, so not all the information will be available for
iProphet in the second analysis.  Also, for your large analysis that is
currently failing in Petunia you might consider running the tool on the
commandline.

For your second question, the NSP model can be disabled on the commandline
using the NONSP flag.  The ProteinProphet NSP model is implemented
differently in iProphet and in ProteinProphet.  Although, in theory
applying the models both times could be problematic due to their
similarity, in practice the models are different enought that during
testing I have not observed deleterious effects from using both the
iProphet and the ProteinProphet NSP models. You can try running the tools
in different ways and comparing the performance.  Using both NSP models is
the current default and you would have to explicitly disable the models
when you run each tool.

I hope this helps.

-David




On Tue, Jun 19, 2018 at 5:29 PM, <pbell.scie...@gmail.com> wrote:

> Hi All,
>
> I have 2 questions I'd be grateful if people could help answer:
>
> 1)
> Is it valid to combine multiple iprophet.pep.xml files by passing through
> iprophet for a second time? - alternatively, is it valid to combine a
> single iprophet.pep.xml file with interact.pep.xml files in iprophet?
>
> I am trying to combine a lot of different experiments / search engines
> results etc, and have been combining in iprophet - but I appear to have
> maxed out the number interact.pep.xml files to pass into iprophet. Beyond a
> certain number of files (doesn't appear to be file-specific), iProphet
> fails. As a workaround, I wondered if I could simply run half of the files
> through iProphet, then combine the resulting file with the remaining files
> to be run, by running iprophet again prior to running protein prophet. -
> Would this be valid?
>
> 2)
> I attended a TPP course last year in which the course notes stated that
> NSP should be switched off in iProphet, if NSP model is to be used in
> protein prophet.
>
> I am using petunia (running protein prophet on the iprophet results), and
> I cannot see a NSP option in the protein prophet parameters. Does this mean
> that NSP is not being used when I run protein prophet? ... (i.e. am I ok to
> leave NSP on in iProphet?)
>
>
> Thanks
> Pete
>
>
>
>
>
>
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