X Hunter

X Hunter matches experimental tandem mass spectra to annotated library spectra to identify peptide sequences across proteomes.

Key Features:

• Library construction: Compiles tandem mass spectra annotated with peptide sequences and averages spectra associated with identical peptide sequences, sequence modifications, and parent ion charges.
• Database integration: Uses annotated spectra from the Global Proteome Machine Database (GPMDB) as the source of library spectra.
• Spectrum matching: Compares experimental peptide tandem mass spectra against library spectra and computes similarity scores to support peptide identification.
• Organism-specific libraries: Provides annotated tandem mass spectrum libraries for Homo sapiens, Mus musculus, and Saccharomyces cerevisiae.
• Software implementation: Implements library-search software to perform spectrum-to-library comparisons and scoring.

Scientific Applications:

• Protein identification: Assigns peptide sequences from tandem mass spectra to enable identification of proteins in complex samples.
• Mass spectrometry data analysis: Provides scored spectrum-to-library matches to support interpretation of MS/MS data.
• Proteome-wide sequence identification: Enables peptide sequence identification across multiple proteomes using organism-specific libraries.

Methodology:

Constructs libraries by averaging GPMDB-annotated tandem mass spectra grouped by peptide sequence, modifications, and parent ion charge; compares experimental MS/MS spectra to these library spectra and scores similarity using a library-search software implementation.