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Topic: Calculated mass error

Hi,

I've noticed some issues with mMass (3.9.0 and now 3.10.0) when they calculate fragment masses. I was using mMass to match ions with a spectra when I noticed it wasn't matching intense ions. When I looked into the problem, I saw that the masses calculated by mMass were incorrect. I've done this in previous versions and it worked fine. I don't know when this bug was introduced.

I compared the masses calculated by mMass (3.10.0) to ProteinProspector (MS-Product) and GPMAW (8.0). The latter two agree with each other (with slight variations in the decimal points), but mMass is out. At first, I thought it was a PTM thing, as I was looking at a phospho peptide, but the problem remains when I remove the modification.

I've got a spreadsheet showing the results, but I obviously can't attach that here, can you provide an e-mail address that I can send it to, so that you can see the problem?

Thanks,

Peter

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Re: Calculated mass error

Hi Peter,
I have briefly checked the fragmentation tool and I have not found any differences between mMass and MS-Product. Please send me your spreadsheet to support(at)mmass.org and I will check it.

Thanks,
Martin

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Re: Calculated mass error

According to your data, this is just Monoisotopic vs. Average mass problem on your side...
Martin