Spectral Library Search Task

Protein database searching and spectral library searching has been the two most widely used peptide dentification methods. However, each search strategy has their own shortcoming. Database searching lack intensities value thus not accurate enough and spectral library searching can’t identify spectra which are not included in library. To address these limitations, we developed a hybrid search strategy, combining protein database search and spectral library search to improve the identification rate as well as accuracy. This hybrid search strategy, as well as spectral library generation algorithm, and visualization tool were integrated into MetaMorpheus, improving accuracy and sensitivity in the peptide identification and making it easy to visualize and evaluate the PSMs results.

Creating a New Hybrid Task

• Load .raw or .mzML data files
• Load database(s) and spectral library(.msp) If you want to generate your own library, click here to learn how to generate spectral libraries by MetaMorpheus
• Select "New Search Task" tab
• Search Parameters: Make the appropriate adjustments to the settings. Try to use standard search tolerance (15ppm precursor and 25ppm product for high resolution orbitrap data)
• Modifications: Use standard modifications (e.g. fixed carbamidomethylation, variable oxidation and localize all modifications checked if using .xml database)
• Select "Add the Search Task"
• Run all tasks!

What should I expect?

Compared with normal search task (database search only), spectral angles values will be found in Allpsms.tsv file.