MS_Piano

MS_Piano annotates product ion peaks in collision-induced dissociation (CID) tandem mass spectra of peptides and N-glycopeptides to support spectral quality assessment and peptide/N-glycopeptide identification.

Key Features:

• Reliable annotation: Annotates peaks in high- and low-resolution CID tandem mass spectra by matching each peak to possible product ions derived from supplied peptide sequences, charge states, and optional modifications.
• Mass difference calculation: Calculates the mass difference between measured and theoretical m/z values for each annotated peak.
• Spectral quality assessment: Evaluates spectral quality using the ratio between the sum of unannotated versus all peak intensities in the top 20 peaks and the intensity of the highest unannotated peak.
• Ion class labeling: Labels product ions from peptides, glycans, and glycopeptides with distinct class-type colors within spectra.
• Validation and quality control: Assists validation of peptide and N-glycopeptide identifications from database and library searches and provides quality control metrics for developing custom peptide mass spectral libraries.

Scientific Applications:

• Proteomics: Supports accurate peptide identification and spectral quality control in mass spectrometry-based proteomic analyses.
• Glycoproteomics: Facilitates confident determination and validation of N-glycosylation sites in glycoprotein studies.
• Spectral library development: Provides metrics and validation used to optimize and verify custom peptide mass spectral libraries.
• Functional and disease studies: Supports investigations into protein function and disease mechanisms where glycosylation is relevant by improving annotation confidence.

Methodology:

MS_Piano accepts CID tandem mass spectra with specified peptide sequences, charge states, and potential modifications; matches peaks to possible product ions, computes mass differences between measured and theoretical m/z values, evaluates spectral quality using the two specified metrics (unannotated/total intensity ratio in the top 20 peaks and highest unannotated peak intensity), and labels product ions by class (peptide, glycan, glycopeptide) with distinct colors.