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Posted by Patrick Emery (June 20, 2018)

Mascot Distiller 2.7: Farewell to re-gridding

We recently released Mascot Distiller 2.7. The main new feature of this release is a change to how peak detection works on raw profile datasets that have been saved as sparse, or compressed data, with runs of zero values dropped. Common examples of this are Thermo Orbitrap and Sciex Analyst datasets saved as profile data. For these types of data, [...]

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Posted by Patrick Emery (January 16, 2017)

How many of you are there in there? Processing and searching chimeric MS/MS spectra with Mascot Distiller and Mascot Server

In the typical shotgun proteomics experiment, the assumption is that each MS/MS spectrum is derived from a single precursor selected by the Mass Spectrometer for fragmentation. However, in practice, near isobaric precursors can co-elute and undergo co-fragmentation resulting in chimeric MS/MS spectra containing fragments from multiple different precursor peptides. With high resolution data, it is possible for these overlapping isotope [...]

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Posted by John Cottrell (March 14, 2016)

Some peaks are more equal than others

When you look at the details of a peptide match in the Mascot Peptide View report, only a small number of the peaks may be labelled in the spectrum graphic and highlighted in the table of fragment masses. We often got challenged about this: "Why haven’t you labelled these other peaks that clearly match?". So, in Mascot 2.3, we added [...]

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Posted by John Cottrell (April 30, 2014)

Peak list arcana*

This article addresses some aspects of how the information in a peak list is used by Mascot, what is not used, and how the peak list is processed prior to a search. These things are all in the manual, but can be difficult to find, short of reading it from cover to cover. Fragment charge is not used in the [...]

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Posted by John Cottrell (August 2, 2013)

Current challenges in quantitative proteomics

"Current challenges in software solutions for mass spectrometry-based quantitative proteomics" is a recent paper in Amino Acids by a group of expert authors that describes ten areas of particular difficulty in data processing for quantitation. Full text is available online at Springer Link. I would argue that Mascot Distiller meets almost all of these challenges. Obviously, I have to declare [...]

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