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Articles tagged: quantitation
Mascot Distiller quantitates more proteins with machine learning
Mascot Distiller can now use machine learning with LFQ, TMT and other quantitation methods, thanks to API changes made in the recent Mascot Server 3.1 release. Machine learning typically increases the number of identified peptides at a fixed false discovery rate, which often leads to a substantial boost in the number of proteins quantified. We demonstrate this with an LFQ [...]
Mascot workflow for LC-MS/MS data
Data analysis in mass spectrometry proteomics is complex and, nowadays, almost entirely software driven. Processing a raw file, peptide identification by database searching, protein inference and protein quantitation all have many steps and built-in assumptions, not to mention a huge number of parameters. Software continues to evolve as does best practice. Whether you are new to mass spectrometry proteomics or [...]
Tutorial: Creating custom reports in Mascot Distiller
Mascot Distiller 2.8 reports are written in Python, a commonly used programming language, and use Mascot Parser to access the search and quantitation results. We supply a range of standard reports, including reports for quality, clustering and statistical analysis, which we took a look at in an earlier blog article. In addition to these, you can develop your own reports [...]
Mascot Daemon Export Extender
Mascot Daemon has two features to help with automation and creating pipelines. The first is the AutoExport feature that allows you to configure and export a report into a CSV file, mzIdentML file or other format that Mascot Server supports with the options you choose. This happens once the search is complete. The lesser known but more powerful feature is [...]
Complementary reporter ion clusters in TMT/TMTpro labeling
We recently received a support request about complementary ions in TMTpro labeling. Complementary ions are formed during fragmentation, where the precursor loses the reporter ion and carbon monoxide, leaving behind the peptide and the balance region of the label. Complementary ion spacing is similar to reporter ions but the mass varies depending on peptide mass. The customer was concerned that [...]
Reporting quantitation datasets with Mascot Distiller 2.8
In previous versions of Distiller, reporting of quantitation results was handled using XSLT transformation of the XML export of the quantitation results. XSLT is a powerful language, but it’s not commonly used, so writing custom reports could be an uphill stuggle. In Mascot Distiller 2.8, reports are written in Python and use Mascot Parser to access the search and quantitation [...]
Divide and conquer: Fractionated Label Free Quantitation in Mascot Distiller 2.8.2
We have recently released Mascot Distiller 2.8.2. The headline new feature is support for Label-Free Quantitation of fractionated samples. With Mascot Distiller 2.8, individual raw files in a project are aligned against a consensus generated by roughly aligning and combining the total ion chromatograms (TICs) of each raw file. If a peptide match is found in one sample file and [...]
Improving precursor quantitation results with ion mobility filtering
One of the major new features in Mascot Distiller 2.8 is support for raw data files from the Bruker timsTOF instrument. timsTOF combines an ion mobility dimension with QTOF, allowing an additional separation dimension. The instrument can use this to help separate MS/MS spectra from otherwise isobaric peptides. Mascot Distiller 2.8 can use the precursor ion mobility values for identified [...]
Global thinking: Label Free Quantitation in Mascot Distiller 2.8
Mascot Distiller supports a wide range of precursor based quantitation methods, including two label-free methods, which we call Replicate and Average. Version 2.8 makes significant improvements to the Replicate method. This is the method for label-free quantitation based on the relative intensities of extracted ion chromatograms (XICs) for precursors in multiple data sets aligned using mass and elution time. Replicate [...]
How much cashmere is in this sweater?
Textiles made from luxurious animal hair like cashmere and angora can fetch a high price. Bloomberg reported that cashmere garments alone were worth $1.4 billion in global exports in 2016. Big money attracts fraudsters, and sometimes products claiming to be cashmere could be something else, like rat fur. In this context, the International Organization for Standardization (ISO) has recently standardised [...]